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  • C++ - checking if a class has a certain method at compile time

    - by jetwolf
    Here's a question for the C++ gurus out there. Is there a way to check at compile time where a type has a certain method, and do one thing if it does, and another thing if it doesn't? Basically, I have a template function template <typename T> void function(T t); and I it to behave a certain way if T has a method g(), and another way if it doesn't. Perhaps there is something that can be used together with boost's enable_if? Something like this: template <typename T> enable_if<has_method<T, g, void ()>, void>::type function(T t) { // Superior implementation calling t.g() } template <typename T> disable_if<has_method<T, g, void ()>, void>::type function(T t) { // Inferior implementation in the case where T doesn't have a method g() } "has_method" would be something that preferably checks both that T has a method named 'g', and that the method has the correct signature (in this case, void ()). Any ideas?

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  • Getting list of all existing vtables.

    - by Patrick
    In my application I have quite some void-pointers (this is because of historical reasons, application was originally written in pure C). In one of my modules I know that the void-pointers points to instances of classes that could inherit from a known base class, but I cannot be 100% sure of it. Therefore, doing a dynamic_cast on the void-pointer might give problems. Possibly, the void-pointer even points to a plain-struct (so no vptr in the struct). I would like to investigate the first 4 bytes of the memory the void-pointer is pointing to, to see if this is the address of the valid vtable. I know this is platform, maybe even compiler-version-specific, but it could help me in moving the application forward, and getting rid of all the void-pointers over a limited time period (let's say 3 years). Is there a way to get a list of all vtables in the application, or a way to check whether a pointer points to a valid vtable, and whether that instance pointing to the vtable inherits from a known base class?

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  • Clicking Elements in Android Doesn't Display the Correct Values

    - by Devin
    I apologize if this code looks a bit like a mess (considering the length); I figured I'd just include everything that goes on in my program at the moment. I'm attempting to create a fairly simple Tic Tac Toe app for Android. I've set up my UI nicely so far so that there are a "grid" of TextViews. As a sort of "debug" right now, I have it so that when one clicks on a TextView, it should display the value of buttonId in a message box. Right now, it displays the correct assigned value for the first element I click, but no matter what I click afterwards, it always just displays the first value buttonID had. I attempted to debug it but couldn't exactly find a point where it would pull the old value (to the best of my knowledge, it reassigned the value). There's a good possibility I'm missing something small, because this is my first Android project (of any note). Can someone help get different values of buttonId to appear or point out the error in my logic? The code: package com.TicTacToe.app; import com.TicTacToe.app.R; //Other import statements public class TicTacToe extends Activity { public String player = "X"; public int ALERT_ID; public int buttonId; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); //Sets up instances of UI elements final TextView playerText = (TextView)findViewById(R.id.CurrentPlayerDisp); final Button button = (Button) findViewById(R.id.SetPlayer); final TextView location1 = (TextView)findViewById(R.id.location1); final TextView location2 = (TextView)findViewById(R.id.location2); final TextView location3 = (TextView)findViewById(R.id.location3); final TextView location4 = (TextView)findViewById(R.id.location4); final TextView location5 = (TextView)findViewById(R.id.location5); final TextView location6 = (TextView)findViewById(R.id.location6); final TextView location7 = (TextView)findViewById(R.id.location7); final TextView location8 = (TextView)findViewById(R.id.location8); final TextView location9 = (TextView)findViewById(R.id.location9); playerText.setText(player); //Handlers for events button.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { // Perform action on click if (player.equals("X")){ player = "O"; playerText.setText(player); } else if(player.equals("O")){ player = "X"; playerText.setText(player); } //Sets up the dialog buttonId = 0; ALERT_ID = 0; onCreateDialog(ALERT_ID); showDialog(ALERT_ID); } }); location1.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //Sets up the dialog buttonId = 1; ALERT_ID = 0; onCreateDialog(ALERT_ID); showDialog(ALERT_ID); } }); location2.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //Sets up the dialog buttonId = 2; ALERT_ID = 0; onCreateDialog(ALERT_ID); showDialog(ALERT_ID); } }); location3.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //Sets up the dialog buttonId = 3; ALERT_ID = 0; onCreateDialog(ALERT_ID); showDialog(ALERT_ID); } }); location4.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //Sets up the dialog buttonId = 4; ALERT_ID = 0; onCreateDialog(ALERT_ID); showDialog(ALERT_ID); } }); location5.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //Sets up the dialog buttonId = 5; ALERT_ID = 0; onCreateDialog(ALERT_ID); showDialog(ALERT_ID); } }); location6.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //Sets up the dialog buttonId = 6; ALERT_ID = 0; onCreateDialog(ALERT_ID); showDialog(ALERT_ID); } }); location7.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //Sets up the dialog buttonId = 7; ALERT_ID = 0; onCreateDialog(ALERT_ID); showDialog(ALERT_ID); } }); location8.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //Sets up the dialog buttonId = 8; ALERT_ID = 0; onCreateDialog(ALERT_ID); showDialog(ALERT_ID); } }); location9.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //Sets up the dialog buttonId = 9; ALERT_ID = 0; onCreateDialog(ALERT_ID); showDialog(ALERT_ID); } }); } protected Dialog onCreateDialog(int id){ String msgString = "You are on spot " + buttonId; AlertDialog.Builder builder = new AlertDialog.Builder(this); builder.setMessage(msgString) .setCancelable(false) .setNeutralButton("Ok", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int id) { dialog.cancel(); } }); AlertDialog alert = builder.create(); return alert; } }

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  • Issue when rotating a UIScrollView

    - by leachianus.gecko
    I am having issues trying to get the pageControl sample code to work with rotation. I managed to get it to rotate but it does not visually load correctly until I start to scroll (then it works fine). Any Idea on how I can fix this problem? Here is a link to the project if you want to see it in action. This code is based off the PageControl example apple has provided. here is the code: #import "ScrollingViewController.h" #import "MyViewController.h" @interface ScrollingViewController (PrivateMethods) - (void)loadScrollViewWithPage:(int)page; @end @implementation ScrollingViewController @synthesize scrollView; @synthesize viewControllers; - (void)viewDidLoad { amount = 5; [super viewDidLoad]; [self setupPage]; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; } - (void)viewDidUnload { [scrollView release]; } - (void)dealloc { [super dealloc]; } - (void)setupPage { NSMutableArray *controllers = [[NSMutableArray alloc] init]; for (unsigned i = 0; i < amount; i++) { [controllers addObject:[NSNull null]]; } self.viewControllers = controllers; [controllers release]; // a page is the width of the scroll view scrollView.pagingEnabled = YES; scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * amount, 200); scrollView.showsHorizontalScrollIndicator = NO; scrollView.showsVerticalScrollIndicator = NO; scrollView.scrollsToTop = NO; scrollView.delegate = self; [self loadScrollViewWithPage:0]; [self loadScrollViewWithPage:1]; } #pragma mark - #pragma mark UIScrollViewDelegate stuff - (void)scrollViewDidScroll:(UIScrollView *)_scrollView { if (pageControlIsChangingPage) { return; } /* * We switch page at 50% across */ CGFloat pageWidth = _scrollView.frame.size.width; int dog = floor((_scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1; // pageControl.currentPage = page; [self loadScrollViewWithPage:dog - 1]; [self loadScrollViewWithPage:dog]; [self loadScrollViewWithPage:dog + 1]; } - (void)loadScrollViewWithPage:(int)page { if (page < 0) return; if (page >= amount) return; MyViewController *controller = [viewControllers objectAtIndex:page]; if ((NSNull *)controller == [NSNull null]) { controller = [[MyViewController alloc] initWithPageNumber:page]; [viewControllers replaceObjectAtIndex:page withObject:controller]; [controller release]; } if (nil == controller.view.superview) { CGRect frame = scrollView.frame; frame.origin.x = frame.size.width * page; frame.origin.y = 0; controller.view.frame = frame; [scrollView addSubview:controller.view]; } } - (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation { [self setupPage]; } - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return YES; } @end

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  • Define thread in C++

    - by Vsevywniy
    How do I start a thread using _beginthreadex(), making it execute void myFunction(wchar_t *param);? I try to use this: _beginthread(NULL, 0, myFunction, L"someParam", 0, &ThreadID); but there is compilation error: error C2664: 'beginthreadex' : cannot convert parameter 3 from 'void (_cdecl *)(wchar_t *)' to 'unsigned int (__stdcall *)(void *)'. How I can resolve this error? I seem able to do _beginthread((void(*)(void*))myFunction, 0 , (void *)L"someParam");. But for _beginthreadex() these casts don't seem to work. What do I need to do?

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  • What's the outcome if I use free with new or delete with malloc?

    - by skydoor
    It is a compiler error or runtime error? The code below can be compiled! class Base{ void g(); void h(); }; int main() { Base* p = new Base(); free(p); return 0; } However it can't be compiled with a virtual function if I declare the class Base like this class Base{ virtual void g(); void h(); }; The code below can be compiled all the time, no matter the function is virtual or not. class Base{ void g(); void h(); }; int main() { Base* p = (Base*)malloc(sizeof(Base)); delete p; return 0; }

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  • Why is syslog so much slower than file IO?

    - by ceving
    I wrote a simple test program to measure the performance of the syslog function. This are the results of my test system: (Debian 6.0.2 with Linux 2.6.32-5-amd64) Test Case Calls Payload Duration Thoughput [] [MB] [s] [MB/s] -------------------- ---------- ---------- ---------- ---------- syslog 200000 10.00 7.81 1.28 syslog %s 200000 10.00 9.94 1.01 write /dev/null 200000 10.00 0.03 343.93 printf %s 200000 10.00 0.13 76.29 The test program did 200000 system calls writing 50 Bytes of data during each call. Why is Syslog more than ten times slower than file IO? This is the program I used to perform the test: #include <fcntl.h> #include <stdio.h> #include <string.h> #include <sys/stat.h> #include <sys/time.h> #include <sys/types.h> #include <syslog.h> #include <unistd.h> const int iter = 200000; const char msg[] = "123456789 123456789 123456789 123456789 123456789"; struct timeval t0; struct timeval t1; void start () { gettimeofday (&t0, (void*)0); } void stop () { gettimeofday (&t1, (void*)0); } void report (char *action) { double dt = (double)t1.tv_sec - (double)t0.tv_sec + 1e-6 * ((double)t1.tv_usec - (double)t0.tv_usec); double mb = 1e-6 * sizeof (msg) * iter; if (action == NULL) printf ("Test Case Calls Payload Duration Thoughput \n" " [] [MB] [s] [MB/s] \n" "-------------------- ---------- ---------- ---------- ----------\n"); else { if (strlen (action) > 20) action[20] = 0; printf ("%-20s %-10d %-10.2f %-10.2f %-10.2f\n", action, iter, mb, dt, mb / dt); } } void test_syslog () { int i; openlog ("test_syslog", LOG_PID | LOG_NDELAY, LOG_LOCAL0); start (); for (i = 0; i < iter; i++) syslog (LOG_DEBUG, msg); stop (); closelog (); report ("syslog"); } void test_syslog_format () { int i; openlog ("test_syslog", LOG_PID | LOG_NDELAY, LOG_LOCAL0); start (); for (i = 0; i < iter; i++) syslog (LOG_DEBUG, "%s", msg); stop (); closelog (); report ("syslog %s"); } void test_write_devnull () { int i, fd; fd = open ("/dev/null", O_WRONLY); start (); for (i = 0; i < iter; i++) write (fd, msg, sizeof(msg)); stop (); close (fd); report ("write /dev/null"); } void test_printf () { int i; FILE *fp; fp = fopen ("/tmp/test_printf", "w"); start (); for (i = 0; i < iter; i++) fprintf (fp, "%s", msg); stop (); fclose (fp); report ("printf %s"); } int main (int argc, char **argv) { report (NULL); test_syslog (); test_syslog_format (); test_write_devnull (); test_printf (); }

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  • Java JPanel not showing up....

    - by user69514
    I'm not sure what I am doing wrong, but the text for my JPanels is not showing up. I just get the question number text, but the question is not showing up. Any ideas what I am doing wrong? import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.event.*; class NewFrame extends JFrame { JPanel centerpanel; // For the questions. CardLayout card; // For the centerpanel. JTextField tf; // Used in question 1. boolean // Store selections for Q2. q2Option1, q2Option2, q2Option3, q2Option4; JList q4List; // For question 4. double // Score on each question. q1Score = 0, q2Score = 0, q3Score = 0, q4Score = 0; // Constructor. public NewFrame (int width, int height) { this.setTitle ("Snoot Club Membership Test"); this.setResizable (true); this.setSize (width, height); Container cPane = this.getContentPane(); // cPane.setLayout (new BorderLayout()); // First, a welcome message, as a Label. JLabel L = new JLabel ("<html><b>Are you elitist enough for our exclusive club?" + " <br>Fill out the form and find out</b></html>"); L.setForeground (Color.blue); cPane.add (L, BorderLayout.NORTH); // Now the center panel with the questions. card = new CardLayout (); centerpanel = new JPanel (); centerpanel.setLayout (card); centerpanel.setOpaque (false); // Each question will be created in a separate method. // The cardlayout requires a label as second parameter. centerpanel.add (firstQuestion (), "1"); centerpanel.add (secondQuestion(), "2"); centerpanel.add (thirdQuestion(), "3"); centerpanel.add (fourthQuestion(), "4"); cPane.add (centerpanel, BorderLayout.CENTER); // Next, a panel of four buttons at the bottom. // The four buttons: quit, submit, next-question, previous-question. JPanel bottomPanel = getBottomPanel (); cPane.add (bottomPanel, BorderLayout.SOUTH); // Finally, show the frame. this.setVisible (true); } // No-parameter constructor. public NewFrame () { this (500, 300); } // The first question uses labels for the question and // gets input via a textfield. A panel containing all // these things is returned. The question asks for // a vacation destination: the more exotic the location, // the higher the score. JPanel firstQuestion () { // We will package everything into a panel and return the panel. JPanel subpanel = new JPanel (); // We will place things in a single column, so // a GridLayout with one column is appropriate. subpanel.setLayout (new GridLayout (8,1)); JLabel L1 = new JLabel ("Question 1:"); L1.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L1); JLabel L2 = new JLabel (" Select a vacation destination"); L2.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L2); JLabel L3 = new JLabel (" 1. Baltimore"); L3.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L3); JLabel L4 = new JLabel (" 2. Disneyland"); L4.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L4); JLabel L5 = new JLabel (" 3. Grand Canyon"); L5.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L5); JLabel L6 = new JLabel (" 4. French Riviera"); L6.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L6); JLabel L7 = new JLabel ("Enter 1,2,3 or 4 below:"); L7.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L7); // Here's the textfield to get user-input. tf = new JTextField (); tf.addActionListener ( new ActionListener () { // This interface has only one method. public void actionPerformed (ActionEvent a) { String q1String = a.getActionCommand(); if (q1String.equals ("2")) q1Score = 2; else if (q1String.equals ("3")) q1Score = 3; else if (q1String.equals ("4")) q1Score = 4; else q1Score = 1; } } ); subpanel.add (tf); return subpanel; } // For the second question, a collection of checkboxes // will be used. More than one selection can be made. // A listener is required for each checkbox. The state // of each checkbox is recorded. JPanel secondQuestion () { JPanel subpanel = new JPanel (); subpanel.setLayout (new GridLayout (7,1)); JLabel L1 = new JLabel ("Question 2:"); L1.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L1); JLabel L2 = new JLabel (" Select ONE OR MORE things that "); L2.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L2); JLabel L3 = new JLabel (" you put into your lunch sandwich"); L3.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L3); // Initialize the selections to false. q2Option1 = q2Option2 = q2Option3 = q2Option4 = false; // First checkbox. JCheckBox c1 = new JCheckBox ("Ham, beef or turkey"); c1.addItemListener ( new ItemListener () { public void itemStateChanged (ItemEvent i) { JCheckBox c = (JCheckBox) i.getSource(); q2Option1 = c.isSelected(); } } ); subpanel.add (c1); // Second checkbox. JCheckBox c2 = new JCheckBox ("Cheese"); c2.addItemListener ( new ItemListener () { // This is where we will react to a change in checkbox. public void itemStateChanged (ItemEvent i) { JCheckBox c = (JCheckBox) i.getSource(); q2Option2 = c.isSelected(); } } ); subpanel.add (c2); // Third checkbox. JCheckBox c3 = new JCheckBox ("Sun-dried Arugula leaves"); c3.addItemListener ( new ItemListener () { public void itemStateChanged (ItemEvent i) { JCheckBox c = (JCheckBox) i.getSource(); q2Option3 = c.isSelected(); } } ); subpanel.add (c3); // Fourth checkbox. JCheckBox c4 = new JCheckBox ("Lemon-enhanced smoked Siberian caviar"); c4.addItemListener ( new ItemListener () { public void itemStateChanged (ItemEvent i) { JCheckBox c = (JCheckBox) i.getSource(); q2Option4 = c.isSelected(); } } ); subpanel.add (c4); return subpanel; } // The third question allows only one among four choices // to be selected. We will use radio buttons. JPanel thirdQuestion () { JPanel subpanel = new JPanel (); subpanel.setLayout (new GridLayout (6,1)); JLabel L1 = new JLabel ("Question 3:"); L1.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L1); JLabel L2 = new JLabel (" And which mustard do you use?"); L2.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L2); // First, create the ButtonGroup instance. // We will add radio buttons to this group. ButtonGroup bGroup = new ButtonGroup(); // First checkbox. JRadioButton r1 = new JRadioButton ("Who cares?"); r1.addItemListener ( new ItemListener () { public void itemStateChanged (ItemEvent i) { JRadioButton r = (JRadioButton) i.getSource(); if (r.isSelected()) q3Score = 1; } } ); bGroup.add (r1); subpanel.add (r1); // Second checkbox. JRadioButton r2 = new JRadioButton ("Safeway Brand"); r2.addItemListener ( new ItemListener () { public void itemStateChanged (ItemEvent i) { JRadioButton r = (JRadioButton) i.getSource(); if (r.isSelected()) q3Score = 2; } } ); bGroup.add (r2); subpanel.add (r2); // Third checkbox. JRadioButton r3 = new JRadioButton ("Fleishman's"); r3.addItemListener ( new ItemListener () { public void itemStateChanged (ItemEvent i) { JRadioButton r = (JRadioButton) i.getSource(); if (r.isSelected()) q3Score = 3; } } ); bGroup.add (r3); subpanel.add (r3); // Fourth checkbox. JRadioButton r4 = new JRadioButton ("Grey Poupon"); r4.addItemListener ( new ItemListener () { public void itemStateChanged (ItemEvent i) { JRadioButton r = (JRadioButton) i.getSource(); if (r.isSelected()) q3Score = 4; } } ); bGroup.add (r4); subpanel.add (r4); return subpanel; } // For the fourth question we will use a drop-down Choice. JPanel fourthQuestion () { JPanel subpanel = new JPanel (); subpanel.setLayout (new GridLayout (3,1)); JLabel L1 = new JLabel ("Question 4:"); L1.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L1); JLabel L2 = new JLabel (" Your movie preference, among these:"); L2.setFont (new Font ("SansSerif", Font.ITALIC, 15)); subpanel.add (L2); // Create a JList with options. String[] movies = { "Lethal Weapon IV", "Titanic", "Saving Private Ryan", "Le Art Movie avec subtitles"}; q4List = new JList (movies); q4Score = 1; q4List.addListSelectionListener ( new ListSelectionListener () { public void valueChanged (ListSelectionEvent e) { q4Score = 1 + q4List.getSelectedIndex(); } } ); subpanel.add (q4List); return subpanel; } void computeResult () { // Clear the center panel. centerpanel.removeAll(); // Create a new panel to display in the center. JPanel subpanel = new JPanel (new GridLayout (5,1)); // Score on question 1. JLabel L1 = new JLabel ("Score on question 1: " + q1Score); L1.setFont (new Font ("Serif", Font.ITALIC, 15)); subpanel.add (L1); // Score on question 2. if (q2Option1) q2Score += 1; if (q2Option2) q2Score += 2; if (q2Option3) q2Score += 3; if (q2Option4) q2Score += 4; q2Score = 0.6 * q2Score; JLabel L2 = new JLabel ("Score on question 2: " + q2Score); L2.setFont (new Font ("Serif", Font.ITALIC, 15)); subpanel.add (L2); // Score on question 3. JLabel L3 = new JLabel ("Score on question 3: " + q3Score); L3.setFont (new Font ("Serif", Font.ITALIC, 15)); subpanel.add (L3); // Score on question 4. JLabel L4 = new JLabel ("Score on question 4: " + q4Score); L4.setFont (new Font ("Serif", Font.ITALIC, 15)); subpanel.add (L4); // Weighted score. double avg = (q1Score + q2Score + q3Score + q4Score) / (double) 4; JLabel L5; if (avg <= 3.5) L5 = new JLabel ("Your average score: " + avg + " - REJECTED!"); else L5 = new JLabel ("Your average score: " + avg + " - WELCOME!"); L5.setFont (new Font ("Serif", Font.BOLD, 20)); //L5.setAlignment (JLabel.CENTER); subpanel.add (L5); // Now add the new subpanel. centerpanel.add (subpanel, "5"); // Need to mark the centerpanel as "altered" centerpanel.invalidate(); // Everything "invalid" (e.g., the centerpanel above) // is now re-computed. this.validate(); } JPanel getBottomPanel () { // Create a panel into which we will place buttons. JPanel bottomPanel = new JPanel (); // A "previous-question" button. JButton backward = new JButton ("Previous question"); backward.setFont (new Font ("Serif", Font.PLAIN | Font.BOLD, 15)); backward.addActionListener ( new ActionListener () { public void actionPerformed (ActionEvent a) { // Go back in the card layout. card.previous (centerpanel); } } ); bottomPanel.add (backward); // A forward button. JButton forward = new JButton ("Next question"); forward.setFont (new Font ("Serif", Font.PLAIN | Font.BOLD, 15)); forward.addActionListener ( new ActionListener () { public void actionPerformed (ActionEvent a) { // Go forward in the card layout. card.next (centerpanel); } } ); bottomPanel.add (forward); // A submit button. JButton submit = new JButton ("Submit"); submit.setFont (new Font ("Serif", Font.PLAIN | Font.BOLD, 15)); submit.addActionListener ( new ActionListener () { public void actionPerformed (ActionEvent a) { // Perform submit task. computeResult(); } } ); bottomPanel.add (submit); JButton quitb = new JButton ("Quit"); quitb.setFont (new Font ("Serif", Font.PLAIN | Font.BOLD, 15)); quitb.addActionListener ( new ActionListener () { public void actionPerformed (ActionEvent a) { System.exit (0); } } ); bottomPanel.add (quitb); return bottomPanel; } } public class Survey { public static void main (String[] argv) { NewFrame nf = new NewFrame (600, 300); } }

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  • JGoodies HashMap

    - by JohnMcClane
    Hi, I'm trying to build a chart program using presentation model. Using JGoodies for data binding was relatively easy for simple types like strings or numbers. But I can't figure out how to use it on a hashmap. I'll try to explain how the chart works and what my problem is: A chart consists of DataSeries, a DataSeries consists of DataPoints. I want to have a data model and to be able to use different views on the same model (e.g. bar chart, pie chart,...). Each of them consists of three classes. For example: DataPointModel: holds the data model (value, label, category) DataPointViewModel: extends JGoodies PresentationModel. wraps around DataPointModel and holds view properties like font and color. DataPoint: abstract class, extends JComponent. Different Views must subclass and implement their own ui. Binding and creating the data model was easy, but i don't know how to bind my data series model. package at.onscreen.chart; import java.beans.PropertyChangeListener; import java.beans.PropertyChangeSupport; import java.beans.PropertyVetoException; import java.util.Collection; import java.util.HashMap; import java.util.Iterator; public class DataSeriesModel { public static String PROPERTY_DATAPOINT = "dataPoint"; public static String PROPERTY_DATAPOINTS = "dataPoints"; public static String PROPERTY_LABEL = "label"; public static String PROPERTY_MAXVALUE = "maxValue"; /** * holds the data points */ private HashMap dataPoints; /** * the label for the data series */ private String label; /** * the maximum data point value */ private Double maxValue; /** * the model supports property change notification */ private PropertyChangeSupport propertyChangeSupport; /** * default constructor */ public DataSeriesModel() { this.maxValue = Double.valueOf(0); this.dataPoints = new HashMap(); this.propertyChangeSupport = new PropertyChangeSupport(this); } /** * constructor * @param label - the series label */ public DataSeriesModel(String label) { this.dataPoints = new HashMap(); this.maxValue = Double.valueOf(0); this.label = label; this.propertyChangeSupport = new PropertyChangeSupport(this); } /** * full constructor * @param label - the series label * @param dataPoints - an array of data points */ public DataSeriesModel(String label, DataPoint[] dataPoints) { this.dataPoints = new HashMap(); this.propertyChangeSupport = new PropertyChangeSupport(this); this.maxValue = Double.valueOf(0); this.label = label; for (int i = 0; i < dataPoints.length; i++) { this.addDataPoint(dataPoints[i]); } } /** * full constructor * @param label - the series label * @param dataPoints - a collection of data points */ public DataSeriesModel(String label, Collection dataPoints) { this.dataPoints = new HashMap(); this.propertyChangeSupport = new PropertyChangeSupport(this); this.maxValue = Double.valueOf(0); this.label = label; for (Iterator it = dataPoints.iterator(); it.hasNext();) { this.addDataPoint(it.next()); } } /** * adds a new data point to the series. if the series contains a data point with same id, it will be replaced by the new one. * @param dataPoint - the data point */ public void addDataPoint(DataPoint dataPoint) { String category = dataPoint.getCategory(); DataPoint oldDataPoint = this.getDataPoint(category); this.dataPoints.put(category, dataPoint); this.setMaxValue(Math.max(this.maxValue, dataPoint.getValue())); this.propertyChangeSupport.firePropertyChange(PROPERTY_DATAPOINT, oldDataPoint, dataPoint); } /** * returns the data point with given id or null if not found * @param uid - the id of the data point * @return the data point or null if there is no such point in the table */ public DataPoint getDataPoint(String category) { return this.dataPoints.get(category); } /** * removes the data point with given id from the series, if present * @param category - the data point to remove */ public void removeDataPoint(String category) { DataPoint dataPoint = this.getDataPoint(category); this.dataPoints.remove(category); if (dataPoint != null) { if (dataPoint.getValue() == this.getMaxValue()) { Double maxValue = Double.valueOf(0); for (Iterator it = this.iterator(); it.hasNext();) { DataPoint itDataPoint = it.next(); maxValue = Math.max(itDataPoint.getValue(), maxValue); } this.setMaxValue(maxValue); } } this.propertyChangeSupport.firePropertyChange(PROPERTY_DATAPOINT, dataPoint, null); } /** * removes all data points from the series * @throws PropertyVetoException */ public void removeAll() { this.setMaxValue(Double.valueOf(0)); this.dataPoints.clear(); this.propertyChangeSupport.firePropertyChange(PROPERTY_DATAPOINTS, this.getDataPoints(), null); } /** * returns the maximum of all data point values * @return the maximum of all data points */ public Double getMaxValue() { return this.maxValue; } /** * sets the max value * @param maxValue - the max value */ protected void setMaxValue(Double maxValue) { Double oldMaxValue = this.getMaxValue(); this.maxValue = maxValue; this.propertyChangeSupport.firePropertyChange(PROPERTY_MAXVALUE, oldMaxValue, maxValue); } /** * returns true if there is a data point with given category * @param category - the data point category * @return true if there is a data point with given category, otherwise false */ public boolean contains(String category) { return this.dataPoints.containsKey(category); } /** * returns the label for the series * @return the label for the series */ public String getLabel() { return this.label; } /** * returns an iterator over the data points * @return an iterator over the data points */ public Iterator iterator() { return this.dataPoints.values().iterator(); } /** * returns a collection of the data points. the collection supports removal, but does not support adding of data points. * @return a collection of data points */ public Collection getDataPoints() { return this.dataPoints.values(); } /** * returns the number of data points in the series * @return the number of data points */ public int getSize() { return this.dataPoints.size(); } /** * adds a PropertyChangeListener * @param listener - the listener */ public void addPropertyChangeListener(PropertyChangeListener listener) { this.propertyChangeSupport.addPropertyChangeListener(listener); } /** * removes a PropertyChangeListener * @param listener - the listener */ public void removePropertyChangeListener(PropertyChangeListener listener) { this.propertyChangeSupport.removePropertyChangeListener(listener); } } package at.onscreen.chart; import java.beans.PropertyVetoException; import java.util.Collection; import java.util.Iterator; import com.jgoodies.binding.PresentationModel; public class DataSeriesViewModel extends PresentationModel { /** * default constructor */ public DataSeriesViewModel() { super(new DataSeriesModel()); } /** * constructor * @param label - the series label */ public DataSeriesViewModel(String label) { super(new DataSeriesModel(label)); } /** * full constructor * @param label - the series label * @param dataPoints - an array of data points */ public DataSeriesViewModel(String label, DataPoint[] dataPoints) { super(new DataSeriesModel(label, dataPoints)); } /** * full constructor * @param label - the series label * @param dataPoints - a collection of data points */ public DataSeriesViewModel(String label, Collection dataPoints) { super(new DataSeriesModel(label, dataPoints)); } /** * full constructor * @param model - the data series model */ public DataSeriesViewModel(DataSeriesModel model) { super(model); } /** * adds a data point to the series * @param dataPoint - the data point */ public void addDataPoint(DataPoint dataPoint) { this.getBean().addDataPoint(dataPoint); } /** * returns true if there is a data point with given category * @param category - the data point category * @return true if there is a data point with given category, otherwise false */ public boolean contains(String category) { return this.getBean().contains(category); } /** * returns the data point with given id or null if not found * @param uid - the id of the data point * @return the data point or null if there is no such point in the table */ public DataPoint getDataPoint(String category) { return this.getBean().getDataPoint(category); } /** * returns a collection of the data points. the collection supports removal, but does not support adding of data points. * @return a collection of data points */ public Collection getDataPoints() { return this.getBean().getDataPoints(); } /** * returns the label for the series * @return the label for the series */ public String getLabel() { return this.getBean().getLabel(); } /** * sets the max value * @param maxValue - the max value */ public Double getMaxValue() { return this.getBean().getMaxValue(); } /** * returns the number of data points in the series * @return the number of data points */ public int getSize() { return this.getBean().getSize(); } /** * returns an iterator over the data points * @return an iterator over the data points */ public Iterator iterator() { return this.getBean().iterator(); } /** * removes all data points from the series * @throws PropertyVetoException */ public void removeAll() { this.getBean().removeAll(); } /** * removes the data point with given id from the series, if present * @param category - the data point to remove */ public void removeDataPoint(String category) { this.getBean().removeDataPoint(category); } } package at.onscreen.chart; import java.beans.PropertyChangeEvent; import java.beans.PropertyChangeListener; import java.beans.PropertyVetoException; import java.util.Collection; import java.util.Iterator; import javax.swing.JComponent; public abstract class DataSeries extends JComponent implements PropertyChangeListener { /** * the model */ private DataSeriesViewModel model; /** * default constructor */ public DataSeries() { this.model = new DataSeriesViewModel(); this.model.addPropertyChangeListener(this); this.createComponents(); } /** * constructor * @param label - the series label */ public DataSeries(String label) { this.model = new DataSeriesViewModel(label); this.model.addPropertyChangeListener(this); this.createComponents(); } /** * full constructor * @param label - the series label * @param dataPoints - an array of data points */ public DataSeries(String label, DataPoint[] dataPoints) { this.model = new DataSeriesViewModel(label, dataPoints); this.model.addPropertyChangeListener(this); this.createComponents(); } /** * full constructor * @param label - the series label * @param dataPoints - a collection of data points */ public DataSeries(String label, Collection dataPoints) { this.model = new DataSeriesViewModel(label, dataPoints); this.model.addPropertyChangeListener(this); this.createComponents(); } /** * full constructor * @param model - the model */ public DataSeries(DataSeriesViewModel model) { this.model = model; this.model.addPropertyChangeListener(this); this.createComponents(); } /** * creates, binds and configures UI components. * data point properties can be created here as components or be painted in paintComponent. */ protected abstract void createComponents(); @Override public void propertyChange(PropertyChangeEvent evt) { this.repaint(); } /** * adds a data point to the series * @param dataPoint - the data point */ public void addDataPoint(DataPoint dataPoint) { this.model.addDataPoint(dataPoint); } /** * returns true if there is a data point with given category * @param category - the data point category * @return true if there is a data point with given category, otherwise false */ public boolean contains(String category) { return this.model.contains(category); } /** * returns the data point with given id or null if not found * @param uid - the id of the data point * @return the data point or null if there is no such point in the table */ public DataPoint getDataPoint(String category) { return this.model.getDataPoint(category); } /** * returns a collection of the data points. the collection supports removal, but does not support adding of data points. * @return a collection of data points */ public Collection getDataPoints() { return this.model.getDataPoints(); } /** * returns the label for the series * @return the label for the series */ public String getLabel() { return this.model.getLabel(); } /** * sets the max value * @param maxValue - the max value */ public Double getMaxValue() { return this.model.getMaxValue(); } /** * returns the number of data points in the series * @return the number of data points */ public int getDataPointCount() { return this.model.getSize(); } /** * returns an iterator over the data points * @return an iterator over the data points */ public Iterator iterator() { return this.model.iterator(); } /** * removes all data points from the series * @throws PropertyVetoException */ public void removeAll() { this.model.removeAll(); } /** * removes the data point with given id from the series, if present * @param category - the data point to remove */ public void removeDataPoint(String category) { this.model.removeDataPoint(category); } /** * returns the data series view model * @return - the data series view model */ public DataSeriesViewModel getViewModel() { return this.model; } /** * returns the data series model * @return - the data series model */ public DataSeriesModel getModel() { return this.model.getBean(); } } package at.onscreen.chart.builder; import java.util.Collection; import net.miginfocom.swing.MigLayout; import at.onscreen.chart.DataPoint; import at.onscreen.chart.DataSeries; import at.onscreen.chart.DataSeriesViewModel; public class BuilderDataSeries extends DataSeries { /** * default constructor */ public BuilderDataSeries() { super(); } /** * constructor * @param label - the series label */ public BuilderDataSeries(String label) { super(label); } /** * full constructor * @param label - the series label * @param dataPoints - an array of data points */ public BuilderDataSeries(String label, DataPoint[] dataPoints) { super(label, dataPoints); } /** * full constructor * @param label - the series label * @param dataPoints - a collection of data points */ public BuilderDataSeries(String label, Collection dataPoints) { super(label, dataPoints); } /** * full constructor * @param model - the model */ public BuilderDataSeries(DataSeriesViewModel model) { super(model); } @Override protected void createComponents() { this.setLayout(new MigLayout()); /* * * I want to add a new BuilderDataPoint for each data point in the model. * I want the BuilderDataPoints to be synchronized with the model. * e.g. when a data point is removed from the model, the BuilderDataPoint shall be removed * from the BuilderDataSeries * */ } } package at.onscreen.chart.builder; import javax.swing.JFormattedTextField; import javax.swing.JTextField; import at.onscreen.chart.DataPoint; import at.onscreen.chart.DataPointModel; import at.onscreen.chart.DataPointViewModel; import at.onscreen.chart.ValueFormat; import com.jgoodies.binding.adapter.BasicComponentFactory; import com.jgoodies.binding.beans.BeanAdapter; public class BuilderDataPoint extends DataPoint { /** * default constructor */ public BuilderDataPoint() { super(); } /** * constructor * @param category - the category */ public BuilderDataPoint(String category) { super(category); } /** * constructor * @param value - the value * @param label - the label * @param category - the category */ public BuilderDataPoint(Double value, String label, String category) { super(value, label, category); } /** * full constructor * @param model - the model */ public BuilderDataPoint(DataPointViewModel model) { super(model); } @Override protected void createComponents() { BeanAdapter beanAdapter = new BeanAdapter(this.getModel(), true); ValueFormat format = new ValueFormat(); JFormattedTextField value = BasicComponentFactory.createFormattedTextField(beanAdapter.getValueModel(DataPointModel.PROPERTY_VALUE), format); this.add(value, "w 80, growx, wrap"); JTextField label = BasicComponentFactory.createTextField(beanAdapter.getValueModel(DataPointModel.PROPERTY_LABEL)); this.add(label, "growx, wrap"); JTextField category = BasicComponentFactory.createTextField(beanAdapter.getValueModel(DataPointModel.PROPERTY_CATEGORY)); this.add(category, "growx, wrap"); } } To sum it up: I need to know how to bind a hash map property to JComponent.components property. JGoodies is in my opinion not very well documented, I spent a long time searching through the internet, but I did not find any solution to my problem. Hope you can help me.

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  • .LazyInitializationException when adding to a list that is held within a entity class using hibernat

    - by molleman
    Right so i am working with hibernate gilead and gwt to persist my data on users and files of a website. my users have a list of file locations. i am using annotations to map my classes to the database. i am getting a org.hibernate.LazyInitializationException when i try to add file locations to the list that is held in the user class. this is a method below that is overridden from a external file upload servlet class that i am using. when the file uploads it calls this method. the user1 is loaded from the database elsewhere. the exception occurs at user1.getFileLocations().add(fileLocation); . i dont understand it really at all.! any help would be great. the stack trace of the error is below public String executeAction(HttpServletRequest request, List<FileItem> sessionFiles) throws UploadActionException { for (FileItem item : sessionFiles) { if (false == item.isFormField()) { try { YFUser user1 = (YFUser)getSession().getAttribute(SESSION_USER); // This is the location where a file will be stored String fileLocationString = "/Users/Stefano/Desktop/UploadedFiles/" + user1.getUsername(); File fl = new File(fileLocationString); fl.mkdir(); // so here i will create the a file container for my uploaded file File file = File.createTempFile("upload-", ".bin",fl); // this is where the file is written to disk item.write(file); // the FileLocation object is then created FileLocation fileLocation = new FileLocation(); fileLocation.setLocation(fileLocationString); //test System.out.println("file path = "+file.getPath()); user1.getFileLocations().add(fileLocation); //the line above is where the exception occurs } catch (Exception e) { throw new UploadActionException(e.getMessage()); } } removeSessionFileItems(request); } return null; } //This is the class file for a Your Files User @Entity @Table(name = "yf_user_table") public class YFUser implements Serializable,ILightEntity { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "user_id",nullable = false) private int userId; @Column(name = "username") private String username; @Column(name = "password") private String password; @Column(name = "email") private String email; @ManyToMany(cascade = CascadeType.ALL) @JoinTable(name = "USER_FILELOCATION", joinColumns = { @JoinColumn(name = "user_id") }, inverseJoinColumns = { @JoinColumn(name = "locationId") }) private List<FileLocation> fileLocations = new ArrayList<FileLocation>() ; public YFUser(){ } public int getUserId() { return userId; } private void setUserId(int userId) { this.userId = userId; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public List<FileLocation> getFileLocations() { if(fileLocations ==null){ fileLocations = new ArrayList<FileLocation>(); } return fileLocations; } public void setFileLocations(List<FileLocation> fileLocations) { this.fileLocations = fileLocations; } /* public void addFileLocation(FileLocation location){ fileLocations.add(location); }*/ @Override public void addProxyInformation(String property, Object proxyInfo) { // TODO Auto-generated method stub } @Override public String getDebugString() { // TODO Auto-generated method stub return null; } @Override public Object getProxyInformation(String property) { // TODO Auto-generated method stub return null; } @Override public boolean isInitialized(String property) { // TODO Auto-generated method stub return false; } @Override public void removeProxyInformation(String property) { // TODO Auto-generated method stub } @Override public void setInitialized(String property, boolean initialised) { // TODO Auto-generated method stub } @Override public Object getValue() { // TODO Auto-generated method stub return null; } } @Entity @Table(name = "fileLocationTable") public class FileLocation implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "locationId", updatable = false, nullable = false) private int ieId; @Column (name = "location") private String location; /* private List uploadedUsers = new ArrayList(); */ public FileLocation(){ } public int getIeId() { return ieId; } private void setIeId(int ieId) { this.ieId = ieId; } public String getLocation() { return location; } public void setLocation(String location) { this.location = location; } /* public List getUploadedUsers() { return uploadedUsers; } public void setUploadedUsers(List<YFUser> uploadedUsers) { this.uploadedUsers = uploadedUsers; } public void addUploadedUser(YFUser user){ uploadedUsers.add(user); } */ } Apr 2, 2010 11:33:12 PM org.hibernate.LazyInitializationException <init> SEVERE: failed to lazily initialize a collection of role: com.example.client.YFUser.fileLocations, no session or session was closed org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.example.client.YFUser.fileLocations, no session or session was closed at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:380) at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:372) at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:365) at org.hibernate.collection.AbstractPersistentCollection.write(AbstractPersistentCollection.java:205) at org.hibernate.collection.PersistentBag.add(PersistentBag.java:297) at com.example.server.TestServiceImpl.saveFileLocation(TestServiceImpl.java:132) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at net.sf.gilead.gwt.PersistentRemoteService.processCall(PersistentRemoteService.java:174) at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:224) at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62) at javax.servlet.http.HttpServlet.service(HttpServlet.java:713) at javax.servlet.http.HttpServlet.service(HttpServlet.java:806) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:324) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505) at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843) at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647) at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380) at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:396) at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488) Apr 2, 2010 11:33:12 PM net.sf.gilead.core.PersistentBeanManager clonePojo INFO: Third party instance, not cloned : org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.example.client.YFUser.fileLocations, no session or session was closed

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  • Binary Cosine Cofficient

    - by hairyyak
    I was given the following forumulae for calculating this sim=|QnD| / v|Q|v|D| I went ahed and implemented a class to compare strings consisting of a series of words #pragma once #include <vector> #include <string> #include <iostream> #include <vector> using namespace std; class StringSet { public: StringSet(void); StringSet( const string the_strings[], const int no_of_strings); ~StringSet(void); StringSet( const vector<string> the_strings); void add_string( const string the_string); bool remove_string( const string the_string); void clear_set(void); int no_of_strings(void) const; friend ostream& operator <<(ostream& outs, StringSet& the_strings); friend StringSet operator *(const StringSet& first, const StringSet& second); friend StringSet operator +(const StringSet& first, const StringSet& second); double binary_coefficient( const StringSet& the_second_set); private: vector<string> set; }; #include "StdAfx.h" #include "StringSet.h" #include <iterator> #include <algorithm> #include <stdexcept> #include <iostream> #include <cmath> StringSet::StringSet(void) { } StringSet::~StringSet(void) { } StringSet::StringSet( const vector<string> the_strings) { set = the_strings; } StringSet::StringSet( const string the_strings[], const int no_of_strings) { copy( the_strings, &the_strings[no_of_strings], back_inserter(set)); } void StringSet::add_string( const string the_string) { try { if( find( set.begin(), set.end(), the_string) == set.end()) { set.push_back(the_string); } else { //String is already in the set. throw domain_error("String is already in the set"); } } catch( domain_error e) { cout << e.what(); exit(1); } } bool StringSet::remove_string( const string the_string) { //Found the occurrence of the string. return it an iterator pointing to it. vector<string>::iterator iter; if( ( iter = find( set.begin(), set.end(), the_string) ) != set.end()) { set.erase(iter); return true; } return false; } void StringSet::clear_set(void) { set.clear(); } int StringSet::no_of_strings(void) const { return set.size(); } ostream& operator <<(ostream& outs, StringSet& the_strings) { vector<string>::const_iterator const_iter = the_strings.set.begin(); for( ; const_iter != the_strings.set.end(); const_iter++) { cout << *const_iter << " "; } cout << endl; return outs; } //This function returns the union of the two string sets. StringSet operator *(const StringSet& first, const StringSet& second) { vector<string> new_string_set; new_string_set = first.set; for( unsigned int i = 0; i < second.set.size(); i++) { vector<string>::const_iterator const_iter = find(new_string_set.begin(), new_string_set.end(), second.set[i]); //String is new - include it. if( const_iter == new_string_set.end() ) { new_string_set.push_back(second.set[i]); } } StringSet the_set(new_string_set); return the_set; } //This method returns the intersection of the two string sets. StringSet operator +(const StringSet& first, const StringSet& second) { //For each string in the first string look though the second and see if //there is a matching pair, in which case include the string in the set. vector<string> new_string_set; vector<string>::const_iterator const_iter = first.set.begin(); for ( ; const_iter != first.set.end(); ++const_iter) { //Then search through the entire second string to see if //there is a duplicate. vector<string>::const_iterator const_iter2 = second.set.begin(); for( ; const_iter2 != second.set.end(); const_iter2++) { if( *const_iter == *const_iter2 ) { new_string_set.push_back(*const_iter); } } } StringSet new_set(new_string_set); return new_set; } double StringSet::binary_coefficient( const StringSet& the_second_set) { double coefficient; StringSet intersection = the_second_set + set; coefficient = intersection.no_of_strings() / sqrt((double) no_of_strings()) * sqrt((double)the_second_set.no_of_strings()); return coefficient; } However when I try and calculate the coefficient using the following main function: // Exercise13.cpp : main project file. #include "stdafx.h" #include <boost/regex.hpp> #include "StringSet.h" using namespace System; using namespace System::Runtime::InteropServices; using namespace boost; //This function takes as input a string, which //is then broken down into a series of words //where the punctuaction is ignored. StringSet break_string( const string the_string) { regex re; cmatch matches; StringSet words; string search_pattern = "\\b(\\w)+\\b"; try { // Assign the regular expression for parsing. re = search_pattern; } catch( regex_error& e) { cout << search_pattern << " is not a valid regular expression: \"" << e.what() << "\"" << endl; exit(1); } sregex_token_iterator p(the_string.begin(), the_string.end(), re, 0); sregex_token_iterator end; for( ; p != end; ++p) { string new_string(p->first, p->second); String^ copy_han = gcnew String(new_string.c_str()); String^ copy_han2 = copy_han->ToLower(); char* str2 = (char*)(void*)Marshal::StringToHGlobalAnsi(copy_han2); string new_string2(str2); words.add_string(new_string2); } return words; } int main(array<System::String ^> ^args) { StringSet words = break_string("Here is a string, with some; words"); StringSet words2 = break_string("There is another string,"); cout << words.binary_coefficient(words2); return 0; } I get an index which is 1.5116 rather than a value from 0 to 1. Does anybody have a clue why this is the case? Any help would be appreciated.

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  • Solving the EXC_BAD_ACCESS in WhatATool Part 2

    - by Allen
    #import <Cocoa/Cocoa.h> @interface PolygonShape : NSObject { int numberOfSides, maximumNumberOfSides, minimumNumberOfSides; } @property (readwrite) int numberOfSides, maximumNumberOfSides, minimumNumberOfSides; @property (readonly) float angleInDegrees, angleInRadians; @property (readonly) NSString * name; @property (readonly) NSString * description; -(id) init; -(void) setNumberOfSides:(int)sides; -(void) setMinimumNumberOfSides:(int)min; -(void) setMaximumNumberOfSides:(int)max; -(float) angleInDegrees; -(float) angleInRadians; -(NSString *) name; -(id) initWithNumberOfSides:(int) sides minimumNumberOfSides:(int) min maximumNumberOfSides:(int) max; -(NSString *) description; -(void) dealloc; @end #import "PolygonShape.h" @implementation PolygonShape -(id) init { return [self initWithNumberOfSides:4 minimumNumberOfSides:3 maximumNumberOfSides:5]; } @synthesize numberOfSides, minimumNumberOfSides, maximumNumberOfSides, angleInRadians; -(void) setNumberOfSides:(int)sides { numberOfSides = sides; NSLog(@"The number of sides is off limit so the number of sides is %@.",sides); } -(void)setMaximumNumberOfSides:(int)max { if (maximumNumberOfSides <= 12) { maximumNumberOfSides = max; } } -(void)setMinimumNumberOfSides: (int)min { if (minimumNumberOfSides > 2) { minimumNumberOfSides = min; } } - (id)initWithNumberOfSides:(int)sides minimumNumberOfSides:(int)min maximumNumberOfSides:(int)max { if(self=[super init]) { [self setNumberOfSides:(int)sides]; [self setMaximumNumberOfSides:(int)max]; [self setMinimumNumberOfSides: (int)min]; } return self; } -(float) angleInDegrees { float anglesInDegrees = (180 * (numberOfSides - 2) / numberOfSides); return anglesInDegrees; } -(float)angleInRadiants { float anglesInRadiants = ((180 * (numberOfSides - 2) / numberOfSides) * (180 / M_PI)); return anglesInRadiants; } -(NSString *)name { NSString * output; switch (numberOfSides) { case 3: output = @"Triangle"; break; case 4: output = @"Square"; break; case 5: output = @"Pentagon"; break; case 6: output = @"Hexagon"; break; case 7: output = @"Heptagon"; break; case 8: output = @"Octagon"; break; case 9: output = @"Nonagon"; break; case 10: output = @"Decagon"; break; case 11: output = @"Hendecagon"; break; case 12: output = @"Dodecabgon"; break; default: output = @"Invalid number of sides: %i is greater than maximum of five allowed."; } return output; } -(NSString *)description { NSString * output; NSLog(@"Hello I am a %i-sided polygon (aka a %@) with angles of %f degrees (%f radians).", numberOfSides, output, [self angleInDegrees], [self angleInRadiants]); return [self description]; } -(void)dealloc { [super dealloc]; } @end #import <Foundation/Foundation.h> #import "PolygonShape.h" void PrintPathInfo() { NSLog(@"Section 1"); NSLog(@"--------------------"); NSString *path = [@"~" stringByExpandingTildeInPath]; NSLog(@"My home folder is at '%@'.", path); NSArray *pathComponent = [path pathComponents]; for (path in pathComponent) { NSLog(@"%@",path); } NSLog(@"--------------------"); NSLog(@"\n"); } void PrintProcessInfo() { NSLog(@"Section 2"); NSLog(@"--------------------"); NSString * processName = [[NSProcessInfo processInfo] processName]; int processIdentifier = [[NSProcessInfo processInfo] processIdentifier]; NSLog(@"Process Name: '%@', Process ID: '%i'", processName, processIdentifier); NSLog(@"--------------------"); NSLog(@"\n"); } void PrintBookmarkInfo() { NSLog(@"Section 3"); NSLog(@"--------------------"); NSArray * keys = [NSArray arrayWithObjects: @"Stanford University", @"Apple", @"CS193P", @"Stanford on iTunes U", @"Stanford Mall", nil]; NSArray * objects = [NSArray arrayWithObjects: [NSURL URLWithString: @"http://www.stanford.edu"], @"http://www.apple.com", @"http://cs193p.stanford.edu", @"http://itunes.stanford.edu", @"http://stanfordshop.com",nil]; NSMutableDictionary * dictionary = [NSMutableDictionary dictionaryWithObjects:objects forKeys:keys]; NSEnumerator * enumerator = [keys objectEnumerator]; for (id keys in dictionary) { NSLog(@"key: '%@', value: '%@'", keys, [dictionary objectForKey:keys]); } NSLog(@" "); NSLog(@"These are the ones that has the prefix 'Stanford'."); NSLog(@" "); id object; while (object = [enumerator nextObject]) { if ([object hasPrefix: @"Stanford"]) { NSLog(@"key: '%@', value: '%@'", object, [dictionary objectForKey:object]); } } NSLog(@"--------------------"); NSLog(@"\n"); } void PrintIntrospectionInfo() { NSLog(@"Section 4"); NSLog(@"--------------------"); SEL lowercase = @selector (lowercaseString); NSMutableArray * array = [NSMutableArray array]; [array addObject: [NSString stringWithString: @"Here is a string"]]; [array addObject: [NSDictionary dictionary]]; [array addObject: [NSURL URLWithString: @"http://www.stanford.edu"]]; [array addObject: [[NSProcessInfo processInfo]processName]]; for (id keys in array) { NSLog(@"\n"); NSLog(@"Class Name: %@", [keys className]); NSLog(@"Is Member of NSString: %@", [keys isMemberOfClass:[NSString class]]?@"Yes":@"No"); NSLog(@"Is Kind of NSString: %@", [keys isKindOfClass:[NSString class]]?@"Yes":@"No"); if ([keys respondsToSelector: lowercase]==YES) { NSLog(@"Responds to lowercaseString: %@",[keys respondsToSelector: lowercase]?@"Yes":@"No"); NSLog(@"lowercaseString is: %@", [keys performSelector: lowercase]); } else { NSLog(@"Responds to lowercaseString: %@",[keys respondsToSelector: lowercase]?@"Yes":@"No" ); } } NSLog(@"--------------------"); } void PrintPolygonInfo() { NSMutableArray * array = [NSMutableArray array]; PolygonShape * polygon1 = [[PolygonShape alloc]initWithNumberOfSides:4 minimumNumberOfSides:3 maximumNumberOfSides:7]; [array addObject:polygon1]; [array description]; PolygonShape * polygon2 = [[PolygonShape alloc]initWithNumberOfSides:6 minimumNumberOfSides:5 maximumNumberOfSides:9]; [array addObject:polygon2]; [array description]; PolygonShape * polygon3 = [[PolygonShape alloc]initWithNumberOfSides:12 minimumNumberOfSides:9 maximumNumberOfSides:12]; [array addObject:polygon3]; [array description]; [array release]; [polygon1 release]; [polygon2 release]; [polygon3 release]; } int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; PrintPathInfo(); PrintProcessInfo(); PrintBookmarkInfo(); PrintIntrospectionInfo(); PrintPolygonInfo(); [pool release]; return 0; } //The result was "EXC_BAD_ACCESS", but I couldn't figure out how to resolve this problem.

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  • C# delegates problem

    - by Mick Taylor
    Hello I am getting the following error from my C# Windows Application: Error 1 No overload for 'CreateLabelInPanel' matches delegate 'WorksOrderStore.ProcessDbConnDetailsDelegate' H:\c\WorksOrderFactory\WorksOrderFactory\WorksOrderClient.cs 43 39 WorksOrderFactory I have 3 .cs files that essentially: Opens a windows Has an option for the users to connect to a db When that is selected, the system will go off and connect to the db, and load some data in (just test data for now) Then using a delegate, the system should do soemthing, which for testing will be to create a label. However I haven't coded this part yet. But I can't build until I get this error sorted. The 3 fiels are called: WorksOrderClient.cs (which is the MAIN) WorksOrderStore.cs LoginBox.cs Here's the code for each file: WorksOrderClient.cs using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using WorksOrderStore; namespace WorksOrderFactory { using WorksOrderStore; public partial class WorksOrderClient : Form { LoginBox lb = new LoginBox(); private static WorksOrderDB wodb = new WorksOrderDB(); private static int num_conns = 0; public WorksOrderClient() { InitializeComponent(); } private void connectToADBToolStripMenuItem_Click(object sender, EventArgs e) { lb.ShowDialog(); lb.Visible = true; } public static bool createDBConnDetObj(string username, string password, string database) { // increase the number of connections num_conns = num_conns + 1; // create the connection object wodb.AddDbConnDetails(username, password, database, num_conns); // create a new delegate object associated with the static // method WorksOrderClient.createLabelInPanel wodb.ProcessDbConnDetails(new ProcessDbConnDetailsDelegate(CreateLabelInPanel)); return true; } static void CreateLabelInPanel(DbConnDetails dbcd) { Console.Write("hellO"); string tmp = (string)dbcd.username; //Console.Write(tmp); } private void WorksOrderClient_Load(object sender, EventArgs e) { } } } WorksOrderStore.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; using WorksOrderFactory; namespace WorksOrderStore { using System.Collections; // Describes a book in the book list: public struct WorksOrder { public string contractor_code { get; set; } // contractor ID public string email_address { get; set; } // contractors email address public string date_issued { get; set; } // date the works order was issued public string wo_ref { get; set; } // works order ref public string status { get; set; } // status ... not used public job_status js { get; set; } // status of this worksorder within this system public WorksOrder(string contractor_code, string email_address, string date_issued, string wo_ref) : this() { this.contractor_code = contractor_code; this.email_address = email_address; this.date_issued = date_issued; this.wo_ref = wo_ref; this.js = job_status.Pending; } } // Declare a delegate type for processing a WorksOrder: //public delegate void ProcessWorksOrderDelegate(WorksOrder worksorder); // Maintains a worksorder database. public class WorksOrderDB { // List of all worksorders in the database: ArrayList list = new ArrayList(); // Add a worksorder to the database: public void AddWorksOrder(string contractor_code, string email_address, string date_issued, string wo_ref) { list.Add(new WorksOrder(contractor_code, email_address, date_issued, wo_ref)); } // Call a passed-in delegate on each pending works order to process it: /*public void ProcessPendingWorksOrders(ProcessWorksOrderDelegate processWorksOrder) { foreach (WorksOrder wo in list) { if (wo.js.Equals(job_status.Pending)) // Calling the delegate: processWorksOrder(wo); } }*/ // Add a DbConnDetails to the database: public void AddDbConnDetails(string username, string password, string database, int conn_num) { list.Add(new DbConnDetails(username, password, database, conn_num)); } // Call a passed-in delegate on each dbconndet to process it: public void ProcessDbConnDetails(ProcessDbConnDetailsDelegate processDBConnDetails) { foreach (DbConnDetails wo in list) { processDBConnDetails(wo); } } } // statuses for worksorders in this system public enum job_status { Pending, InProgress, Completed } public struct DbConnDetails { public string username { get; set; } // username public string password { get; set; } // password public string database { get; set; } // database public int conn_num { get; set; } // this objects connection number. public ArrayList woList { get; set; } // list of works orders for this connection // this constructor just sets the db connection details // the woList array will get created later .. not a lot later but a bit. public DbConnDetails(string username, string password, string database, int conn_num) : this() { this.username = username; this.password = password; this.database = database; this.conn_num = conn_num; woList = new ArrayList(); } } // Declare a delegate type for processing a DbConnDetails: public delegate void ProcessDbConnDetailsDelegate(DbConnDetails dbConnDetails); } and LoginBox.cs using System; using System.Collections.Generic; using System.ComponentModel; using System.Drawing; using System.Data; using System.Linq; using System.Text; using System.Windows.Forms; namespace WorksOrderFactory { public partial class LoginBox : Form { public LoginBox() { InitializeComponent(); } private void LoginBox_Load(object sender, EventArgs e) { this.Visible = true; this.Show(); //usernameText.Text = "Username"; //new Font(usernameText.Font, FontStyle.Italic); } private void cancelBtn_Click(object sender, EventArgs e) { this.Close(); } private void loginBtn_Click(object sender, EventArgs e) { // set up a connection details object. bool success = WorksOrderClient.createDBConnDetObj(usernameText.Text, passwordText.Text, databaseText.Text); } private void LoginBox_Load_1(object sender, EventArgs e) { } } } Any ideas?? Cheers, m

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  • How to sort & Group in Android?

    - by crickpatel0024
    I have ArrayList and I want to sort and group all data by header in Android. How it is possible in Android? please help me.below me from owner And set header Me And Joe Manager From owner And set Header in listview. How to do that in Android? My code in below:: public class Request extends Activity { private String assosiatetoken; private ArrayList<All_Request_data_dto> list = new ArrayList<All_Request_data_dto>(); ListView lv; Button back; private Spinner spndata; String[] reqspinner = { "Request Date", "Last Update", "Type", "Owner", "State" }; ArrayAdapter<String> adapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.request); assosiatetoken = MyApplication.getToken(); new doinbackground(this).execute(); back = (Button) findViewById(R.id.button1); spndata = (Spinner) findViewById(R.id.list_all_quize_req); adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, reqspinner); spndata.setAdapter(adapter); lv = (ListView) findViewById(R.id.listrequestdata); lv.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> a, View v, int position, long id) { Intent edit = new Intent(Request.this, Request_webview.class); // edit.putExtra("Cat_url", url_link); startActivity(edit); } }); spndata.setOnItemSelectedListener(new OnItemSelectedListener() { public void onItemSelected(AdapterView<?> arg0, View arg1, int position, long arg3) { switch (position) { case 0: list = DBAdpter.requestUserData(assosiatetoken); Collections.sort(list, byDate1); // Collections.reverse(list); for (int i = 0; i < list.size(); i++) { if (list.get(i).submitDate != null) { lv.setAdapter(new MyListAdapter( getApplicationContext(), list)); } } break; case 1: list = DBAdpter.requestUserData(assosiatetoken); Collections.sort(list, byDate); for (int i = 0; i < list.size(); i++) { if (list.get(i).lastModifiedDate != null) { lv.setAdapter(new MyListAdapter( getApplicationContext(), list)); } } break; case 2: list = DBAdpter.requestUserData(assosiatetoken); Collections.sort(list, byDate3); // Collections.reverse(list); for (int i = 0; i < list.size(); i++) { if (list.get(i).state != null) { lv.setAdapter(new MyListAdapter( getApplicationContext(), list)); } } break; case 3: list = DBAdpter.requestUserData(assosiatetoken); for (int i = 0; i < list.size(); i++) { lv.setAdapter(new MyListAdapter( getApplicationContext(), list)); } break; default: break; } } public void onNothingSelected(AdapterView<?> arg0) { } }); back.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { finish(); } }); } static final Comparator<All_Request_data_dto> byDate = new Comparator<All_Request_data_dto>() { SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy hh:mm:ss a"); public int compare(All_Request_data_dto ord1, All_Request_data_dto ord2) { java.util.Date d1 = null; java.util.Date d2 = null; try { d1 = sdf.parse(ord1.lastModifiedDate); d2 = sdf.parse(ord2.lastModifiedDate); } catch (java.text.ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } return (d1.getTime() > d2.getTime() ? -1 : 1); // descending // return (d1.getTime() > d2.getTime() ? 1 : -1); //ascending } }; static final Comparator<All_Request_data_dto> byDate1 = new Comparator<All_Request_data_dto>() { SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy hh:mm:ss a"); public int compare(All_Request_data_dto ord1, All_Request_data_dto ord2) { java.util.Date d1 = null; java.util.Date d2 = null; try { d1 = sdf.parse(ord1.submitDate); d2 = sdf.parse(ord2.submitDate); } catch (java.text.ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } return (d1.getTime() > d2.getTime() ? -1 : 1); // descending // return (d1.getTime() > d2.getTime() ? 1 : -1); //ascending } }; static final Comparator<All_Request_data_dto> byDate3 = new Comparator<All_Request_data_dto>() { public int compare(All_Request_data_dto ord1, All_Request_data_dto ord2) { String d1 = null; String d2 = null; d1 = ord1.state; d2 = ord2.state; return d1.compareToIgnoreCase(d2); } }; class doinbackground extends AsyncTask<Void, Void, Void> { ProgressDialog pd; private Context ctx; public doinbackground(Context c) { ctx = c; } @Override protected void onPreExecute() { super.onPreExecute(); pd = new ProgressDialog(ctx); pd.setMessage("Loading..."); pd.show(); } @Override protected Void doInBackground(Void... Params) { return null; } @Override protected void onPostExecute(Void result) { super.onPostExecute(result); pd.cancel(); } } public class MyListAdapter extends BaseAdapter { private ArrayList<All_Request_data_dto> list; public MyListAdapter(Context mContext, ArrayList<All_Request_data_dto> list) { this.list = list; } public int getCount() { return list.size(); } public All_Request_data_dto getItem(int position) { return list.get(position); } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { // if (convertView == null) { LayoutInflater inflator = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE); convertView = inflator.inflate(R.layout.custom_request_data, null); TextView req_id = (TextView) convertView.findViewById(R.id.req_txt); TextView date = (TextView) convertView.findViewById(R.id.date_txt); TextView owner = (TextView) convertView .findViewById(R.id.owner_txt); TextView state = (TextView) convertView .findViewById(R.id.state_txt); req_id.setText(list.get(position).requestId + " - " + list.get(position).title); date.setText(list.get(position).lastModifiedDate + " - " + list.get(position).submitDate); owner.setText(list.get(position).owner); state.setText(list.get(position).state); // } return convertView; } } }

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  • Trying to get around this Webservice call from Android using AsycTask

    - by Kevin Rave
    I am a fairly beginner in Android Development. I am developing an application that extensively relays on Webservice calls. First screen takes username and password and validates the user by calling the Webservice. If U/P is valid, then I need to fire up the 2nd activity. In that 2nd activity, I need to do 3 calls. But I haven't gotten to the 2nd part yet. In fact, I haven't completed the full coding yet. But I wanted to test if the app is working as far as I've come through. When calling webserivce, I am showing alert dialog. But the app is crashing somewhere. The LoginActivity shows up. When I enter U/P and press Login Button, it crashes. My classes: TaskHandler.java public class TaskHandler { private String URL; private User userObj; private String results; private JSONDownloaderTask task; ; public TaskHandler( String url, User user) { this.URL = url; this.userObj = user; } public String handleTask() { Log.d("Two", "In the function"); task = new JSONDownloaderTask(); Log.d("Three", "In the function"); task.execute(URL); return results; } private class JSONDownloaderTask extends AsyncTask<String, Void, String> { private String username;// = userObj.getUsername(); private String password; //= userObj.getPassword(); public HttpStatus status_code; public JSONDownloaderTask() { Log.d("con", "Success"); this.username = userObj.getUsername(); this.password = userObj.getPassword(); Log.d("User" + this.username , " Pass" + this.password); } private AsyncProgressActivity progressbar = new AsyncProgressActivity(); @Override protected void onPreExecute() { progressbar.showLoadingProgressDialog(); } @Override protected String doInBackground(String... params) { final String url = params[0]; //getString(R.string.api_staging_uri) + "Authenticate/"; // Populate the HTTP Basic Authentitcation header with the username and password HttpAuthentication authHeader = new HttpBasicAuthentication(username, password); HttpHeaders requestHeaders = new HttpHeaders(); requestHeaders.setAuthorization(authHeader); requestHeaders.setAccept(Collections.singletonList(MediaType.APPLICATION_JSON)); // Create a new RestTemplate instance RestTemplate restTemplate = new RestTemplate(); restTemplate.getMessageConverters().add(new MappingJacksonHttpMessageConverter()); try { // Make the network request Log.d(this.getClass().getName(), url); ResponseEntity<Message> response = restTemplate.exchange(url, HttpMethod.GET, new HttpEntity<Object>(requestHeaders), Message.class); status_code = response.getStatusCode(); return response.getBody().toString(); } catch (HttpClientErrorException e) { status_code = e.getStatusCode(); return new Message(0, e.getStatusText(), e.getLocalizedMessage(), "error").toString(); } catch ( Exception e ) { Log.d(this.getClass().getName() ,e.getLocalizedMessage()); return "Unknown Exception"; } } @Override protected void onPostExecute(String result) { progressbar.dismissProgressDialog(); switch ( status_code ) { case UNAUTHORIZED: result = "Invalid username or passowrd"; break; case ACCEPTED: result = "Invalid username or passowrd" + status_code; break; case OK: result = "Successful!"; break; } } } } AsycProgressActivity.java public class AsyncProgressActivity extends Activity { protected static final String TAG = AsyncProgressActivity.class.getSimpleName(); private ProgressDialog progressDialog; private boolean destroyed = false; @Override protected void onDestroy() { super.onDestroy(); destroyed = true; } public void showLoadingProgressDialog() { Log.d("Here", "Progress"); this.showProgressDialog("Authenticating..."); Log.d("Here", "afer p"); } public void showProgressDialog(CharSequence message) { Log.d("Here", "Message"); if (progressDialog == null) { progressDialog = new ProgressDialog(this); progressDialog.setIndeterminate(true); } Log.d("Here", "Message 2"); progressDialog.setMessage(message); progressDialog.show(); } public void dismissProgressDialog() { if (progressDialog != null && !destroyed) { progressDialog.dismiss(); } } } LoginActivity.java public class LoginActivity extends AsyncProgressActivity implements OnClickListener { Button login_button; HttpStatus status_code; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //this.requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.main); login_button = (Button) findViewById(R.id.btnLogin); login_button.setOnClickListener(this); ViewServer.get(this).addWindow(this); } public void onDestroy() { super.onDestroy(); ViewServer.get(this).removeWindow(this); } public void onResume() { super.onResume(); ViewServer.get(this).setFocusedWindow(this); } public void onClick(View v) { if ( v.getId() == R.id.btnLogin ) { User userobj = new User(); String result; userobj.setUsername( ((EditText) findViewById(R.id.username)).getText().toString()); userobj.setPassword(((EditText) findViewById(R.id.password)).getText().toString() ); TaskHandler handler = new TaskHandler(getString(R.string.api_staging_uri) + "Authenticate/", userobj); Log.d(this.getClass().getName(), "One"); result = handler.handleTask(); Log.d(this.getClass().getName(), "After two"); Utilities.showAlert(result, LoginActivity.this); } } Utilities.java public class Utilities { public static void showAlert(String message, Context context) { AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(context); alertDialogBuilder.setTitle("Login"); alertDialogBuilder.setMessage(message) .setCancelable(false) .setPositiveButton("OK",new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog,int id) { dialog.dismiss(); //dialog.cancel(); } }); alertDialogBuilder.setIcon(drawable.ic_dialog_alert); // create alert dialog AlertDialog alertDialog = alertDialogBuilder.create(); // show it alertDialog.show(); } }

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  • graph with database

    - by Flip_novidade
    I need to make two graphs with data coming from the database. I do not know where I am going wrong. If someone can show me the correct way, or provide any examples. must be two graphs, a graph of a specific student another graph of all students thank you public class NotasBean { private Notas notas; private Notas selectedNotas; private List<Notas> filtroNotass; public Notas getNotas() { return notas; } public void setNotas(Notas notas) { this.notas = notas; } public Notas getSelectedNotas() { return selectedNotas; } public void setSelectedNotas(Notas selectedNotas) { this.selectedNotas = selectedNotas; } public List<Notas> getFiltroNotass() { return filtroNotass; } public void setFiltroNotass(List<Notas> filtroNotass) { this.filtroNotass = filtroNotass; } public void prepararAdicionarNotas(){ notas = new Notas(); } public void adicionarNotas(){ dao.NotasDao obj_dao = new dao.NotasDao(); obj_dao.save(notas); } } package dao; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.Statement; import java.util.ArrayList; import java.util.List; import javax.faces.application.FacesMessage; import javax.faces.context.FacesContext; import model.Aluno; import model.Notas; import model.Notas; public class NotasDao { private Conexao obj_conexao; public NotasDao() { obj_conexao = new Conexao(); } public List<Notas> list() { List<Notas> array_registros = new ArrayList<Notas>(); try { String sql = "Select alu_in_ra, dis_st_sigla, ald_fl_p1, ald_fl_p2, ald_fl_p3, ald_fl_trab1, ald_fl_trab2 from cad_aluno_disciplina"; Statement comando_sql = (Statement) obj_conexao.getConexao() .createStatement(); ResultSet obj_result = comando_sql.executeQuery(sql); while (obj_result.next()) { Notas obj_notas = new Notas(); obj_notas.setAlura(obj_result.getInt("alu_in_ra")); obj_notas.setDiscsigla(obj_result.getString("dis_st_sigla")); obj_notas.setP1(obj_result.getInt("ald_fl_p1")); obj_notas.setP2(obj_result.getInt("ald_fl_p2")); obj_notas.setP3(obj_result.getInt("ald_fl_p3")); obj_notas.setTrb1(obj_result.getInt("ald_fl_trab1")); obj_notas.setTrb2(obj_result.getInt("ald_fl_trab2")); array_registros.add(obj_notas); } } catch (Exception e) { System.out.println("Erro no select" + e.getMessage()); } finally { obj_conexao.fecharConexao(); } return array_registros; } public void select(Aluno obj_aluno){ FacesContext mensagem = FacesContext.getCurrentInstance(); try{ String comando_sql = "Select alu_in_ra, dis_st_sigla, ald_fl_p1, ald_fl_p2, ald_fl_p3, ald_fl_trab1, ald_fl_trab2 from cad_aluno_disciplina where alu_in_ra=?"; PreparedStatement obj_sql = (PreparedStatement) obj_conexao.getConexao().prepareStatement(comando_sql); obj_sql.setInt(1, obj_aluno.getRa()); obj_sql.executeUpdate(); mensagem.addMessage(null, new FacesMessage(FacesMessage.SEVERITY_WARN, "Erro ao selecionar aluno!","Snif")); }catch(Exception e){ mensagem.addMessage(null, new FacesMessage(FacesMessage.SEVERITY_FATAL, "Erro na inclusão: "+e.getMessage()," Ocoreu o erro: "+e.getMessage())); }finally{ obj_conexao.fecharConexao(); } return; } }//fecha a classe package model; import java.io.Serializable; public class Notas implements Serializable{ private static final long serialVersionUID = 1L; private int alura; private String discsigla; private float p1; private float p2; private float p3; private float trb1; private float trb2; public Notas() { } public Notas (int alura, String discsigla, float p1, float p2, float p3, float trb1, float trb2){ super(); this.alura=alura; this.discsigla=discsigla; this.p1=p1; this.p2=p2; this.p3=p3; this.trb1=trb1; this.trb2=trb2; } public int getAlura() { return alura; } public void setAlura(int alura) { this.alura = alura; } public String getDiscsigla() { return discsigla; } public void setDiscsigla(String discsigla) { this.discsigla = discsigla; } public float getP1() { return p1; } public void setP1(float p1) { this.p1 = p1; } public float getP2() { return p2; } public void setP2(float p2) { this.p2 = p2; } public float getP3() { return p3; } public void setP3(float p3) { this.p3 = p3; } public float getTrb1() { return trb1; } public void setTrb1(float trb1) { this.trb1 = trb1; } public float getTrb2() { return trb2; } public void setTrb2(float trb2) { this.trb2 = trb2; } } <p:panel header="Grafico Notas Aluno" style="width: 550px"> <p:lineChart id="linear" value="#{notasDao.aluno.alura}" var="notas" xfield="#{notas.alura}" height="300px" width="500px" style="chartStyle"> <p:chartSeries label="Prova 1" value="#{notas.p1}" /> <p:chartSeries label="Prova 2" value="#{notas.p2}" /> <p:chartSeries label="Prova 3" value="#{notas.p3}" /> <p:chartSeries label="Trabalho 1" value="#{notas.trb1}" /> <p:chartSeries label="Trabalho 2" value="#{notas.trb2}" /> </p:lineChart> </p:panel> <p:panel header="Grafico Notas" style="width: 550px"> <p:lineChart id="linear" value="#{notasDao.natas}" var="notas" xfield="#{notas.p1}" height="300px" width="500px" style="chartStyle"> <p:chartSeries label="Prova 1" value="#{notas.p1}" /> <p:chartSeries label="Prova 2" value="#{notas.p2}" /> <p:chartSeries label="Prova 3" value="#{notas.p3}" /> <p:chartSeries label="Trabalho 1" value="#{notas.trb1}" /> <p:chartSeries label="Trabalho 2" value="#{notas.trb2}" /> </p:lineChart> </p:panel>

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  • MvcExtensions – Bootstrapping

    - by kazimanzurrashid
    When you create a new ASP.NET MVC application you will find that the global.asax contains the following lines: namespace MvcApplication1 { // Note: For instructions on enabling IIS6 or IIS7 classic mode, // visit http://go.microsoft.com/?LinkId=9394801 public class MvcApplication : System.Web.HttpApplication { public static void RegisterRoutes(RouteCollection routes) { routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults ); } protected void Application_Start() { AreaRegistration.RegisterAllAreas(); RegisterRoutes(RouteTable.Routes); } } } As the application grows, there are quite a lot of plumbing code gets into the global.asax which quickly becomes a design smell. Lets take a quick look at the code of one of the open source project that I recently visited: public static void RegisterRoutes(RouteCollection routes) { routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute("Default","{controller}/{action}/{id}", new { controller = "Home", action = "Index", id = "" }); } protected override void OnApplicationStarted() { Error += OnError; EndRequest += OnEndRequest; var settings = new SparkSettings() .AddNamespace("System") .AddNamespace("System.Collections.Generic") .AddNamespace("System.Web.Mvc") .AddNamespace("System.Web.Mvc.Html") .AddNamespace("MvcContrib.FluentHtml") .AddNamespace("********") .AddNamespace("********.Web") .SetPageBaseType("ApplicationViewPage") .SetAutomaticEncoding(true); #if DEBUG settings.SetDebug(true); #endif var viewFactory = new SparkViewFactory(settings); ViewEngines.Engines.Add(viewFactory); #if !DEBUG PrecompileViews(viewFactory); #endif RegisterAllControllersIn("********.Web"); log4net.Config.XmlConfigurator.Configure(); RegisterRoutes(RouteTable.Routes); Factory.Load(new Components.WebDependencies()); ModelBinders.Binders.DefaultBinder = new Binders.GenericBinderResolver(Factory.TryGet<IModelBinder>); ValidatorConfiguration.Initialize("********"); HtmlValidationExtensions.Initialize(ValidatorConfiguration.Rules); } private void OnEndRequest(object sender, System.EventArgs e) { if (((HttpApplication)sender).Context.Handler is MvcHandler) { CreateKernel().Get<ISessionSource>().Close(); } } private void OnError(object sender, System.EventArgs e) { CreateKernel().Get<ISessionSource>().Close(); } protected override IKernel CreateKernel() { return Factory.Kernel; } private static void PrecompileViews(SparkViewFactory viewFactory) { var batch = new SparkBatchDescriptor(); batch.For<HomeController>().For<ManageController>(); viewFactory.Precompile(batch); } As you can see there are quite a few of things going on in the above code, Registering the ViewEngine, Compiling the Views, Registering the Routes/Controllers/Model Binders, Settings up Logger, Validations and as you can imagine the more it becomes complex the more things will get added in the application start. One of the goal of the MVCExtensions is to reduce the above design smell. Instead of writing all the plumbing code in the application start, it contains BootstrapperTask to register individual services. Out of the box, it contains BootstrapperTask to register Controllers, Controller Factory, Action Invoker, Action Filters, Model Binders, Model Metadata/Validation Providers, ValueProvideraFactory, ViewEngines etc and it is intelligent enough to automatically detect the above types and register into the ASP.NET MVC Framework. Other than the built-in tasks you can create your own custom task which will be automatically executed when the application starts. When the BootstrapperTasks are in action you will find the global.asax pretty much clean like the following: public class MvcApplication : UnityMvcApplication { public void ErrorLog_Filtering(object sender, ExceptionFilterEventArgs e) { Check.Argument.IsNotNull(e, "e"); HttpException exception = e.Exception.GetBaseException() as HttpException; if ((exception != null) && (exception.GetHttpCode() == (int)HttpStatusCode.NotFound)) { e.Dismiss(); } } } The above code is taken from my another open source project Shrinkr, as you can see the global.asax is longer cluttered with any plumbing code. One special thing you have noticed that it is inherited from the UnityMvcApplication rather than regular HttpApplication. There are separate version of this class for each IoC Container like NinjectMvcApplication, StructureMapMvcApplication etc. Other than executing the built-in tasks, the Shrinkr also has few custom tasks which gets executed when the application starts. For example, when the application starts, we want to ensure that the default users (which is specified in the web.config) are created. The following is the custom task that is used to create those default users: public class CreateDefaultUsers : BootstrapperTask { protected override TaskContinuation ExecuteCore(IServiceLocator serviceLocator) { IUserRepository userRepository = serviceLocator.GetInstance<IUserRepository>(); IUnitOfWork unitOfWork = serviceLocator.GetInstance<IUnitOfWork>(); IEnumerable<User> users = serviceLocator.GetInstance<Settings>().DefaultUsers; bool shouldCommit = false; foreach (User user in users) { if (userRepository.GetByName(user.Name) == null) { user.AllowApiAccess(ApiSetting.InfiniteLimit); userRepository.Add(user); shouldCommit = true; } } if (shouldCommit) { unitOfWork.Commit(); } return TaskContinuation.Continue; } } There are several other Tasks in the Shrinkr that we are also using which you will find in that project. To create a custom bootstrapping task you have create a new class which either implements the IBootstrapperTask interface or inherits from the abstract BootstrapperTask class, I would recommend to start with the BootstrapperTask as it already has the required code that you have to write in case if you choose the IBootstrapperTask interface. As you can see in the above code we are overriding the ExecuteCore to create the default users, the MVCExtensions is responsible for populating the  ServiceLocator prior calling this method and in this method we are using the service locator to get the dependencies that are required to create the users (I will cover the custom dependencies registration in the next post). Once the users are created, we are returning a special enum, TaskContinuation as the return value, the TaskContinuation can have three values Continue (default), Skip and Break. The reason behind of having this enum is, in some  special cases you might want to skip the next task in the chain or break the complete chain depending upon the currently running task, in those cases you will use the other two values instead of the Continue. The last thing I want to cover in the bootstrapping task is the Order. By default all the built-in tasks as well as newly created task order is set to the DefaultOrder(a static property), in some special cases you might want to execute it before/after all the other tasks, in those cases you will assign the Order in the Task constructor. For Example, in Shrinkr, we want to run few background services when the all the tasks are executed, so we assigned the order as DefaultOrder + 1. Here is the code of that Task: public class ConfigureBackgroundServices : BootstrapperTask { private IEnumerable<IBackgroundService> backgroundServices; public ConfigureBackgroundServices() { Order = DefaultOrder + 1; } protected override TaskContinuation ExecuteCore(IServiceLocator serviceLocator) { backgroundServices = serviceLocator.GetAllInstances<IBackgroundService>().ToList(); backgroundServices.Each(service => service.Start()); return TaskContinuation.Continue; } protected override void DisposeCore() { backgroundServices.Each(service => service.Stop()); } } That’s it for today, in the next post I will cover the custom service registration, so stay tuned.

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  • Design by Contract with Microsoft .Net Code Contract

    - by Fredrik N
    I have done some talks on different events and summits about Defensive Programming and Design by Contract, last time was at Cornerstone’s Developer Summit 2010. Next time will be at SweNug (Sweden .Net User Group). I decided to write a blog post about of some stuffs I was talking about. Users are a terrible thing! Protect your self from them ”Human users have a gift for doing the worst possible thing at the worst possible time.” – Michael T. Nygard, Release It! The kind of users Michael T. Nygard are talking about is the users of a system. We also have users that uses our code, the users I’m going to focus on is the users of our code. Me and you and another developers. “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” – Martin Fowler Good programmers also writes code that humans know how to use, good programmers also make sure software behave in a predictable manner despise inputs or user actions. Design by Contract   Design by Contract (DbC) is a way for us to make a contract between us (the code writer) and the users of our code. It’s about “If you give me this, I promise to give you this”. It’s not about business validations, that is something completely different that should be part of the domain model. DbC is to make sure the users of our code uses it in a correct way, and that we can rely on the contract and write code in a way where we know that the users will follow the contract. It will make it much easier for us to write code with a contract specified. Something like the following code is something we may see often: public void DoSomething(Object value) { value.DoIKnowThatICanDoThis(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Where “value” can be uses directly or passed to other methods and later be used. What some of us can easily forget here is that the “value” can be “null”. We will probably not passing a null value, but someone else that uses our code maybe will do it. I think most of you (including me) have passed “null” into a method because you don’t know if the argument need to be specified to a valid value etc. I bet most of you also have got the “Null reference exception”. Sometimes this “Null reference exception” can be hard and take time to fix, because we need to search among our code to see where the “null” value was passed in etc. Wouldn’t it be much better if we can as early as possible specify that the value can’t not be null, so the users of our code also know it when the users starts to use our code, and before run time execution of the code? This is where DbC comes into the picture. We can use DbC to specify what we need, and by doing so we can rely on the contract when we write our code. So the code above can actually use the DoIKnowThatICanDoThis() method on the value object without being worried that the “value” can be null. The contract between the users of the code and us writing the code, says that the “value” can’t be null.   Pre- and Postconditions   When working with DbC we are specifying pre- and postconditions.  Precondition is a condition that should be met before a query or command is executed. An example of a precondition is: “The Value argument of the method can’t be null”, and we make sure the “value” isn’t null before the method is called. Postcondition is a condition that should be met when a command or query is completed, a postcondition will make sure the result is correct. An example of a postconditon is “The method will return a list with at least 1 item”. Commands an Quires When using DbC, we need to know what a Command and a Query is, because some principles that can be good to follow are based on commands and queries. A Command is something that will not return anything, like the SQL’s CREATE, UPDATE and DELETE. There are two kinds of Commands when using DbC, the Creation commands (for example a Constructor), and Others. Others can for example be a Command to add a value to a list, remove or update a value etc. //Creation commands public Stack(int size) //Other commands public void Push(object value); public void Remove(); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   A Query, is something that will return something, for example an Attribute, Property or a Function, like the SQL’s SELECT.   There are two kinds of Queries, the Basic Queries  (Quires that aren’t based on another queries), and the Derived Queries, queries that is based on another queries. Here is an example of queries of a Stack: //Basic Queries public int Count; public object this[int index] { get; } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To understand about some principles that are good to follow when using DbC, we need to know about the Commands and different Queries. The 6 Principles When working with DbC, it’s advisable to follow some principles to make it easier to define and use contracts. The following DbC principles are: Separate commands and queries. Separate basic queries from derived queries. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries. For each command, write a postcondition that specifies the value of every basic query. For every query and command, decide on a suitable precondition. Write invariants to define unchanging properties of objects. Before I will write about each of them I want you to now that I’m going to use .Net 4.0 Code Contract. I will in the rest of the post uses a simple Stack (Yes I know, .Net already have a Stack class) to give you the basic understanding about using DbC. A Stack is a data structure where the first item in, will be the first item out. Here is a basic implementation of a Stack where not contract is specified yet: public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } //Is related to Count and this[] Query public object Top() { return this[Count]; } //Creation commands public Stack(uint size) { Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { this[++Count] = value; } public void Remove() { this[Count] = null; Count--; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The Stack is implemented in a way to demonstrate the use of Code Contract in a simple way, the implementation may not look like how you would implement it, so don’t think this is the perfect Stack implementation, only used for demonstration.   Before I will go deeper into the principles I will simply mention how we can use the .Net Code Contract. I mention before about pre- and postcondition, is about “Require” something and to “Ensure” something. When using Code Contract, we will use a static class called “Contract” and is located in he “System.Diagnostics.Contracts” namespace. The contract must be specified at the top or our member statement block. To specify a precondition with Code Contract we uses the Contract.Requires method, and to specify a postcondition, we uses the Contract.Ensure method. Here is an example where both a pre- and postcondition are used: public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The contract above requires that the Count is greater than 0, if not we can’t get the item at the Top of a Stack. We also Ensures that the results (By using the Contract.Result method, we can specify a postcondition that will check if the value returned from a method is correct) of the Top query is equal to this[Count].   1. Separate Commands and Queries   When working with DbC, it’s important to separate Command and Quires. A method should either be a command that performs an Action, or returning information to the caller, not both. By asking a question the answer shouldn’t be changed. The following is an example of a Command and a Query of a Stack: public void Push(object value) public object Top() .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The Push is a command and will not return anything, just add a value to the Stack, the Top is a query to get the item at the top of the stack.   2. Separate basic queries from derived queries There are two different kinds of queries,  the basic queries that doesn’t rely on another queries, and derived queries that uses a basic query. The “Separate basic queries from derived queries” principle is about about that derived queries can be specified in terms of basic queries. So this principles is more about recognizing that a query is a derived query or a basic query. It will then make is much easier to follow the other principles. The following code shows a basic query and a derived query: //Basic Queries public uint Count; //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   We can see that IsEmpty will use the Count query, and that makes the IsEmpty a Derived query.   3. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries.   When the derived query is recognize we can follow the 3ed principle. For each derived query, we can create a postcondition that specifies what result our derived query will return in terms of one or more basic queries. Remember that DbC is about contracts between the users of the code and us writing the code. So we can’t use demand that the users will pass in a valid value, we must also ensure that we will give the users what the users wants, when the user is following our contract. The IsEmpty query of the Stack will use a Count query and that will make the IsEmpty a Derived query, so we should now write a postcondition that specified what results will be returned, in terms of using a basic query and in this case the Count query, //Basic Queries public uint Count; //Derived Queries public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } The Contract.Ensures is used to create a postcondition. The above code will make sure that the results of the IsEmpty (by using the Contract.Result to get the result of the IsEmpty method) is correct, that will say that the IsEmpty will be either true or false based on Count is equal to 0 or not. The postcondition are using a basic query, so the IsEmpty is now following the 3ed principle. We also have another Derived Query, the Top query, it will also need a postcondition and it uses all basic queries. The Result of the Top method must be the same value as the this[] query returns. //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count and this[] Query public object Top() { Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   4. For each command, write a postcondition that specifies the value of every basic query.   For each command we will create a postconditon that specifies the value of basic queries. If we look at the Stack implementation we will have three Commands, one Creation command, the Constructor, and two others commands, Push and Remove. Those commands need a postcondition and they should include basic query to follow the 4th principle. //Creation commands public Stack(uint size) { Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   As you can see the Create command will Ensures that Count will be 0 when the Stack is created, when a Stack is created there shouldn’t be any items in the stack. The Push command will take a value and put it into the Stack, when an item is pushed into the Stack, the Count need to be increased to know the number of items added to the Stack, and we must also make sure the item is really added to the Stack. The postconditon of the Push method will make sure the that old value of the Count (by using the Contract.OldValue we can get the value a Query has before the method is called)  plus 1 will be equal to the Count query, this is the way we can ensure that the Push will increase the Count with one. We also make sure the this[] query will now contain the item we pushed into the Stack. The Remove method must make sure the Count is decreased by one when the top item is removed from the Stack. The Commands is now following the 4th principle, where each command now have a postcondition that used the value of basic queries. Note: The principle says every basic Query, the Remove only used one Query the Count, it’s because this command can’t use the this[] query because an item is removed, so the only way to make sure an item is removed is to just use the Count query, so the Remove will still follow the principle.   5. For every query and command, decide on a suitable precondition.   We have now focused only on postcondition, now time for some preconditons. The 5th principle is about deciding a suitable preconditon for every query and command. If we starts to look at one of our basic queries (will not go through all Queries and commands here, just some of them) the this[] query, we can’t pass an index that is lower then 1 (.Net arrays and list are zero based, but not the stack in this blog post ;)) and the index can’t be lesser than the number of items in the stack. So here we will need a preconditon. public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Think about the Contract as an documentation about how to use the code in a correct way, so if the contract could be specified elsewhere (not part of the method body), we could simply write “return _array[index]” and there is no need to check if index is greater or lesser than Count, because that is specified in a “contract”. The implementation of Code Contract, requires that the contract is specified in the code. As a developer I would rather have this contract elsewhere (Like Spec#) or implemented in a way Eiffel uses it as part of the language. Now when we have looked at one Query, we can also look at one command, the Remove command (You can see the whole implementation of the Stack at the end of this blog post, where precondition is added to more queries and commands then what I’m going to show in this section). We can only Remove an item if the Count is greater than 0. So we can write a precondition that will require that Count must be greater than 0. public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   6. Write invariants to define unchanging properties of objects.   The last principle is about making sure the object are feeling great! This is done by using invariants. When using Code Contract we can specify invariants by adding a method with the attribute ContractInvariantMethod, the method must be private or public and can only contains calls to Contract.Invariant. To make sure the Stack feels great, the Stack must have 0 or more items, the Count can’t never be a negative value to make sure each command and queries can be used of the Stack. Here is our invariant for the Stack object: [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The ObjectInvariant method will be called every time after a Query or Commands is called. Here is the full example using Code Contract:   public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } set { Contract.Requires(index >= 1); Contract.Requires(index <= Count); _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } //Is related to Count and this[] Query public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } //Creation commands public Stack(uint size) { Contract.Requires(size > 0); Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Requires(value != null); Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Summary By using Design By Contract we can make sure the users are using our code in a correct way, and we must also make sure the users will get the expected results when they uses our code. This can be done by specifying contracts. To make it easy to use Design By Contract, some principles may be good to follow like the separation of commands an queries. With .Net 4.0 we can use the Code Contract feature to specify contracts.

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  • Developing web apps using ASP.NET MVC 3, Razor and EF Code First - Part 1

    - by shiju
    In this post, I will demonstrate web application development using ASP. NET MVC 3, Razor and EF code First. This post will also cover Dependency Injection using Unity 2.0 and generic Repository and Unit of Work for EF Code First. The following frameworks will be used for this step by step tutorial. ASP.NET MVC 3 EF Code First CTP 5 Unity 2.0 Define Domain Model Let’s create domain model for our simple web application Category class public class Category {     public int CategoryId { get; set; }     [Required(ErrorMessage = "Name Required")]     [StringLength(25, ErrorMessage = "Must be less than 25 characters")]     public string Name { get; set;}     public string Description { get; set; }     public virtual ICollection<Expense> Expenses { get; set; } }   Expense class public class Expense {             public int ExpenseId { get; set; }            public string  Transaction { get; set; }     public DateTime Date { get; set; }     public double Amount { get; set; }     public int CategoryId { get; set; }     public virtual Category Category { get; set; } } We have two domain entities - Category and Expense. A single category contains a list of expense transactions and every expense transaction should have a Category. In this post, we will be focusing on CRUD operations for the entity Category and will be working on the Expense entity with a View Model object in the later post. And the source code for this application will be refactored over time. The above entities are very simple POCO (Plain Old CLR Object) classes and the entity Category is decorated with validation attributes in the System.ComponentModel.DataAnnotations namespace. Now we want to use these entities for defining model objects for the Entity Framework 4. Using the Code First approach of Entity Framework, we can first define the entities by simply writing POCO classes without any coupling with any API or database library. This approach lets you focus on domain model which will enable Domain-Driven Development for applications. EF code first support is currently enabled with a separate API that is runs on top of the Entity Framework 4. EF Code First is reached CTP 5 when I am writing this article. Creating Context Class for Entity Framework We have created our domain model and let’s create a class in order to working with Entity Framework Code First. For this, you have to download EF Code First CTP 5 and add reference to the assembly EntitFramework.dll. You can also use NuGet to download add reference to EEF Code First.    public class MyFinanceContext : DbContext {     public MyFinanceContext() : base("MyFinance") { }     public DbSet<Category> Categories { get; set; }     public DbSet<Expense> Expenses { get; set; }         }   The above class MyFinanceContext is derived from DbContext that can connect your model classes to a database. The MyFinanceContext class is mapping our Category and Expense class into database tables Categories and Expenses using DbSet<TEntity> where TEntity is any POCO class. When we are running the application at first time, it will automatically create the database. EF code-first look for a connection string in web.config or app.config that has the same name as the dbcontext class. If it is not find any connection string with the convention, it will automatically create database in local SQL Express database by default and the name of the database will be same name as the dbcontext class. You can also define the name of database in constructor of the the dbcontext class. Unlike NHibernate, we don’t have to use any XML based mapping files or Fluent interface for mapping between our model and database. The model classes of Code First are working on the basis of conventions and we can also use a fluent API to refine our model. The convention for primary key is ‘Id’ or ‘<class name>Id’.  If primary key properties are detected with type ‘int’, ‘long’ or ‘short’, they will automatically registered as identity columns in the database by default. Primary key detection is not case sensitive. We can define our model classes with validation attributes in the System.ComponentModel.DataAnnotations namespace and it automatically enforces validation rules when a model object is updated or saved. Generic Repository for EF Code First We have created model classes and dbcontext class. Now we have to create generic repository pattern for data persistence with EF code first. If you don’t know about the repository pattern, checkout Martin Fowler’s article on Repository Let’s create a generic repository to working with DbContext and DbSet generics. public interface IRepository<T> where T : class     {         void Add(T entity);         void Delete(T entity);         T GetById(long Id);         IEnumerable<T> All();     }   RepositoryBasse – Generic Repository class public abstract class RepositoryBase<T> where T : class { private MyFinanceContext database; private readonly IDbSet<T> dbset; protected RepositoryBase(IDatabaseFactory databaseFactory) {     DatabaseFactory = databaseFactory;     dbset = Database.Set<T>(); }   protected IDatabaseFactory DatabaseFactory {     get; private set; }   protected MyFinanceContext Database {     get { return database ?? (database = DatabaseFactory.Get()); } } public virtual void Add(T entity) {     dbset.Add(entity);            }        public virtual void Delete(T entity) {     dbset.Remove(entity); }   public virtual T GetById(long id) {     return dbset.Find(id); }   public virtual IEnumerable<T> All() {     return dbset.ToList(); } }   DatabaseFactory class public class DatabaseFactory : Disposable, IDatabaseFactory {     private MyFinanceContext database;     public MyFinanceContext Get()     {         return database ?? (database = new MyFinanceContext());     }     protected override void DisposeCore()     {         if (database != null)             database.Dispose();     } } Unit of Work If you are new to Unit of Work pattern, checkout Fowler’s article on Unit of Work . According to Martin Fowler, the Unit of Work pattern "maintains a list of objects affected by a business transaction and coordinates the writing out of changes and the resolution of concurrency problems." Let’s create a class for handling Unit of Work   public interface IUnitOfWork {     void Commit(); }   UniOfWork class public class UnitOfWork : IUnitOfWork {     private readonly IDatabaseFactory databaseFactory;     private MyFinanceContext dataContext;       public UnitOfWork(IDatabaseFactory databaseFactory)     {         this.databaseFactory = databaseFactory;     }       protected MyFinanceContext DataContext     {         get { return dataContext ?? (dataContext = databaseFactory.Get()); }     }       public void Commit()     {         DataContext.Commit();     } }   The Commit method of the UnitOfWork will call the commit method of MyFinanceContext class and it will execute the SaveChanges method of DbContext class.   Repository class for Category In this post, we will be focusing on the persistence against Category entity and will working on other entities in later post. Let’s create a repository for handling CRUD operations for Category using derive from a generic Repository RepositoryBase<T>.   public class CategoryRepository: RepositoryBase<Category>, ICategoryRepository     {     public CategoryRepository(IDatabaseFactory databaseFactory)         : base(databaseFactory)         {         }                } public interface ICategoryRepository : IRepository<Category> { } If we need additional methods than generic repository for the Category, we can define in the CategoryRepository. Dependency Injection using Unity 2.0 If you are new to Inversion of Control/ Dependency Injection or Unity, please have a look on my articles at http://weblogs.asp.net/shijuvarghese/archive/tags/IoC/default.aspx. I want to create a custom lifetime manager for Unity to store container in the current HttpContext.   public class HttpContextLifetimeManager<T> : LifetimeManager, IDisposable {     public override object GetValue()     {         return HttpContext.Current.Items[typeof(T).AssemblyQualifiedName];     }     public override void RemoveValue()     {         HttpContext.Current.Items.Remove(typeof(T).AssemblyQualifiedName);     }     public override void SetValue(object newValue)     {         HttpContext.Current.Items[typeof(T).AssemblyQualifiedName] = newValue;     }     public void Dispose()     {         RemoveValue();     } }   Let’s create controller factory for Unity in the ASP.NET MVC 3 application. public class UnityControllerFactory : DefaultControllerFactory { IUnityContainer container; public UnityControllerFactory(IUnityContainer container) {     this.container = container; } protected override IController GetControllerInstance(RequestContext reqContext, Type controllerType) {     IController controller;     if (controllerType == null)         throw new HttpException(                 404, String.Format(                     "The controller for path '{0}' could not be found" +     "or it does not implement IController.",                 reqContext.HttpContext.Request.Path));       if (!typeof(IController).IsAssignableFrom(controllerType))         throw new ArgumentException(                 string.Format(                     "Type requested is not a controller: {0}",                     controllerType.Name),                     "controllerType");     try     {         controller= container.Resolve(controllerType) as IController;     }     catch (Exception ex)     {         throw new InvalidOperationException(String.Format(                                 "Error resolving controller {0}",                                 controllerType.Name), ex);     }     return controller; }   }   Configure contract and concrete types in Unity Let’s configure our contract and concrete types in Unity for resolving our dependencies.   private void ConfigureUnity() {     //Create UnityContainer               IUnityContainer container = new UnityContainer()                 .RegisterType<IDatabaseFactory, DatabaseFactory>(new HttpContextLifetimeManager<IDatabaseFactory>())     .RegisterType<IUnitOfWork, UnitOfWork>(new HttpContextLifetimeManager<IUnitOfWork>())     .RegisterType<ICategoryRepository, CategoryRepository>(new HttpContextLifetimeManager<ICategoryRepository>());                 //Set container for Controller Factory                ControllerBuilder.Current.SetControllerFactory(             new UnityControllerFactory(container)); }   In the above ConfigureUnity method, we are registering our types onto Unity container with custom lifetime manager HttpContextLifetimeManager. Let’s call ConfigureUnity method in the Global.asax.cs for set controller factory for Unity and configuring the types with Unity.   protected void Application_Start() {     AreaRegistration.RegisterAllAreas();     RegisterGlobalFilters(GlobalFilters.Filters);     RegisterRoutes(RouteTable.Routes);     ConfigureUnity(); }   Developing web application using ASP.NET MVC 3 We have created our domain model for our web application and also have created repositories and configured dependencies with Unity container. Now we have to create controller classes and views for doing CRUD operations against the Category entity. Let’s create controller class for Category Category Controller   public class CategoryController : Controller {     private readonly ICategoryRepository categoryRepository;     private readonly IUnitOfWork unitOfWork;           public CategoryController(ICategoryRepository categoryRepository, IUnitOfWork unitOfWork)     {         this.categoryRepository = categoryRepository;         this.unitOfWork = unitOfWork;     }       public ActionResult Index()     {         var categories = categoryRepository.All();         return View(categories);     }     [HttpGet]     public ActionResult Edit(int id)     {         var category = categoryRepository.GetById(id);         return View(category);     }       [HttpPost]     public ActionResult Edit(int id, FormCollection collection)     {         var category = categoryRepository.GetById(id);         if (TryUpdateModel(category))         {             unitOfWork.Commit();             return RedirectToAction("Index");         }         else return View(category);                 }       [HttpGet]     public ActionResult Create()     {         var category = new Category();         return View(category);     }           [HttpPost]     public ActionResult Create(Category category)     {         if (!ModelState.IsValid)         {             return View("Create", category);         }                     categoryRepository.Add(category);         unitOfWork.Commit();         return RedirectToAction("Index");     }       [HttpPost]     public ActionResult Delete(int  id)     {         var category = categoryRepository.GetById(id);         categoryRepository.Delete(category);         unitOfWork.Commit();         var categories = categoryRepository.All();         return PartialView("CategoryList", categories);       }        }   Creating Views in Razor Now we are going to create views in Razor for our ASP.NET MVC 3 application.  Let’s create a partial view CategoryList.cshtml for listing category information and providing link for Edit and Delete operations. CategoryList.cshtml @using MyFinance.Helpers; @using MyFinance.Domain; @model IEnumerable<Category>      <table>         <tr>         <th>Actions</th>         <th>Name</th>          <th>Description</th>         </tr>     @foreach (var item in Model) {             <tr>             <td>                 @Html.ActionLink("Edit", "Edit",new { id = item.CategoryId })                 @Ajax.ActionLink("Delete", "Delete", new { id = item.CategoryId }, new AjaxOptions { Confirm = "Delete Expense?", HttpMethod = "Post", UpdateTargetId = "divCategoryList" })                           </td>             <td>                 @item.Name             </td>             <td>                 @item.Description             </td>         </tr>          }       </table>     <p>         @Html.ActionLink("Create New", "Create")     </p> The delete link is providing Ajax functionality using the Ajax.ActionLink. This will call an Ajax request for Delete action method in the CategoryCotroller class. In the Delete action method, it will return Partial View CategoryList after deleting the record. We are using CategoryList view for the Ajax functionality and also for Index view using for displaying list of category information. Let’s create Index view using partial view CategoryList  Index.chtml @model IEnumerable<MyFinance.Domain.Category> @{     ViewBag.Title = "Index"; }    <h2>Category List</h2>    <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.min.js")" type="text/javascript"></script>    <div id="divCategoryList">               @Html.Partial("CategoryList", Model) </div>   We can call the partial views using Html.Partial helper method. Now we are going to create View pages for insert and update functionality for the Category. Both view pages are sharing common user interface for entering the category information. So I want to create an EditorTemplate for the Category information. We have to create the EditorTemplate with the same name of entity object so that we can refer it on view pages using @Html.EditorFor(model => model) . So let’s create template with name Category. Let’s create view page for insert Category information   @model MyFinance.Domain.Category   @{     ViewBag.Title = "Save"; }   <h2>Create</h2>   <script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>   @using (Html.BeginForm()) {     @Html.ValidationSummary(true)     <fieldset>         <legend>Category</legend>                @Html.EditorFor(model => model)               <p>             <input type="submit" value="Create" />         </p>     </fieldset> }   <div>     @Html.ActionLink("Back to List", "Index") </div> ViewStart file In Razor views, we can add a file named _viewstart.cshtml in the views directory  and this will be shared among the all views with in the Views directory. The below code in the _viewstart.cshtml, sets the Layout page for every Views in the Views folder.      @{     Layout = "~/Views/Shared/_Layout.cshtml"; }   Source Code You can download the source code from http://efmvc.codeplex.com/ . The source will be refactored on over time.   Summary In this post, we have created a simple web application using ASP.NET MVC 3 and EF Code First. We have discussed on technologies and practices such as ASP.NET MVC 3, Razor, EF Code First, Unity 2, generic Repository and Unit of Work. In my later posts, I will modify the application and will be discussed on more things. Stay tuned to my blog  for more posts on step by step application building.

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  • WCF RIA Services DomainContext Abstraction Strategies–Say That 10 Times!

    - by dwahlin
    The DomainContext available with WCF RIA Services provides a lot of functionality that can help track object state and handle making calls from a Silverlight client to a DomainService. One of the questions I get quite often in our Silverlight training classes (and see often in various forums and other areas) is how the DomainContext can be abstracted out of ViewModel classes when using the MVVM pattern in Silverlight applications. It’s not something that’s super obvious at first especially if you don’t work with delegates a lot, but it can definitely be done. There are various techniques and strategies that can be used but I thought I’d share some of the core techniques I find useful. To start, let’s assume you have the following ViewModel class (this is from my Silverlight Firestarter talk available to watch online here if you’re interested in getting started with WCF RIA Services): public class AdminViewModel : ViewModelBase { BookClubContext _Context = new BookClubContext(); public AdminViewModel() { if (!DesignerProperties.IsInDesignTool) { LoadBooks(); } } private void LoadBooks() { _Context.Load(_Context.GetBooksQuery(), LoadBooksCallback, null); } private void LoadBooksCallback(LoadOperation<Book> books) { Books = new ObservableCollection<Book>(books.Entities); } } Notice that BookClubContext is being used directly in the ViewModel class. There’s nothing wrong with that of course, but if other ViewModel objects need to load books then code would be duplicated across classes. Plus, the ViewModel has direct knowledge of how to load data and I like to make it more loosely-coupled. To do this I create what I call a “Service Agent” class. This class is responsible for getting data from the DomainService and returning it to a ViewModel. It only knows how to get and return data but doesn’t know how data should be stored and isn’t used with data binding operations. An example of a simple ServiceAgent class is shown next. Notice that I’m using the Action<T> delegate to handle callbacks from the ServiceAgent to the ViewModel object. Because LoadBooks accepts an Action<ObservableCollection<Book>>, the callback method in the ViewModel must accept ObservableCollection<Book> as a parameter. The callback is initiated by calling the Invoke method exposed by Action<T>: public class ServiceAgent { BookClubContext _Context = new BookClubContext(); public void LoadBooks(Action<ObservableCollection<Book>> callback) { _Context.Load(_Context.GetBooksQuery(), LoadBooksCallback, callback); } public void LoadBooksCallback(LoadOperation<Book> lo) { //Check for errors of course...keeping this brief var books = new ObservableCollection<Book>(lo.Entities); var action = (Action<ObservableCollection<Book>>)lo.UserState; action.Invoke(books); } } This can be simplified by taking advantage of lambda expressions. Notice that in the following code I don’t have a separate callback method and don’t have to worry about passing any user state or casting any user state (the user state is the 3rd parameter in the _Context.Load method call shown above). public class ServiceAgent { BookClubContext _Context = new BookClubContext(); public void LoadBooks(Action<ObservableCollection<Book>> callback) { _Context.Load(_Context.GetBooksQuery(), (lo) => { var books = new ObservableCollection<Book>(lo.Entities); callback.Invoke(books); }, null); } } A ViewModel class can then call into the ServiceAgent to retrieve books yet never know anything about the DomainContext object or even know how data is loaded behind the scenes: public class AdminViewModel : ViewModelBase { ServiceAgent _ServiceAgent = new ServiceAgent(); public AdminViewModel() { if (!DesignerProperties.IsInDesignTool) { LoadBooks(); } } private void LoadBooks() { _ServiceAgent.LoadBooks(LoadBooksCallback); } private void LoadBooksCallback(ObservableCollection<Book> books) { Books = books } } You could also handle the LoadBooksCallback method using a lambda if you wanted to minimize code just like I did earlier with the LoadBooks method in the ServiceAgent class.  If you’re into Dependency Injection (DI), you could create an interface for the ServiceAgent type, reference it in the ViewModel and then inject in the object to use at runtime. There are certainly other techniques and strategies that can be used, but the code shown here provides an introductory look at the topic that should help get you started abstracting the DomainContext out of your ViewModel classes when using WCF RIA Services in Silverlight applications.

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  • Trying to run my code and compiler seems to just close after it executes [migrated]

    - by Shane
    I am trying to run a program and the compiler seems to just crash right after it executes ... i have no build errors so i am wondering what the hell is going on ... I am a bit of a novice so all help would be appreciated =). I don't know if you might have time to scan through the code but this is what i have got : using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace ConsoleApplication1 { public class Student { string Fname, Lname, Program ; int Sid ; // Inputting information for students public void InputStudentInfo () { Console.WriteLine ("Please enter your first name") ; Fname = Console.ReadLine() ; Console.WriteLine ("Please enter you last name") ; Lname = Console.ReadLine() ; Console.WriteLine ("Please enter you student ID#") ; Sid = int.Parse(Console.ReadLine()) ; Console.WriteLine ("Enter the Program that you are completeing") ; Program = Console.ReadLine() ; } // Printing information for students public void PrintStudentInfo () { Console.Write (" Your name is " + Fname) ; Console.Write(" " + Lname); Console.WriteLine (" Your student identification number is " + Sid) ; Console.WriteLine (" The program you are registered for is " + Program) ; } /* public void MenuInterface() { Console.WriteLine (" 1. Input Student information" ) ; Console.WriteLine (" 2. Input Course information" ) ; Console.WriteLine (" 3. Input Grade information" ) ; Console.WriteLine (" 4. Print Course information" ) ; Console.WriteLine (" 5. Print Student information" ) ; Console.WriteLine (" 6. Print Grade information" ) ; Console.WriteLine (" 7. Print Student information including Course they are registered in and the grade obtained for that course" ) ; Console.WriteLine (" 8. Print grade info of the course in which student has achieved the highest grade" ) ; Console.WriteLine (" 0. Exit") ; Console.WriteLine (" Please select a choice from 0-8") ; accode = Console.ReadLine(); } */ } public class Course { string course1, course2, course3 ; int Stuid ; // Inputting Course Information public void InputCourseInfo () { Console.WriteLine (" Please re-enter your identification number") ; Stuid = int.Parse(Console.ReadLine()) ; Console.WriteLine (" Enter the name of your first course") ; course1 = Console.ReadLine() ; Console.WriteLine (" Enter the name of your second course") ; course2 = Console.ReadLine() ; Console.WriteLine (" Enter the name of your third course") ; course3 = Console.ReadLine() ; } // Printing Course Information public void PrintCourseInfo () { Console.WriteLine (" Your ID # is " + Stuid) ; Console.Write (" The Courses you selected are " + course1) ; Console.Write("," + course2); Console.Write(" and " + course3); } } public class Grade : Course { int Studentid ; int [] hwgrade ; int [] cwgrade ; int [] midegrade ; int [] finalegrade ; int [] totalgrade ; string coursename ; public Grade ( string cname , int Studentident , int [] homework , int [] classwork , int [] midexam , int [] finalexam) { coursename = cname ; Studentid = Studentident ; hwgrade = homework ; cwgrade = classwork ; midegrade = midexam ; finalegrade = finalexam ; } public string coname { get { return coursename ; } set { coursename = value ; } } public int Studentidenty { get { return Studentid ; } set { Studentid = value ; } } public void InputGradeInfo() { Console.WriteLine (" Please enter your Student ID" ) ; grade.Studentidenty = Console.ReadLine() ; for ( int i = 0; i < 3; i++) { Console.Writeline (" Please enter the Course name" ) ; grade.coname[i] = Console.Readline() ; Console.Writeline (" Please enter your homework grade") ; grade.hwgrade[i] = int.parse(Console.Readline()) ; // ..... } } public void CalcTotalGrade() { for (int i = 0; i < 3; i++) { grade.courseper[i] = (grade.hwgrade[i] + grade.cwgrade[i]) / 2; grade.finalper[i] = (grade.midexam[i] + grade.finalegrade[i]) / 2; grade.totalgrade[i] = (grade.courseper[i] + finalper[i]) / 2; } } public void PrintGradeInfo() { for ( int i = 0; i < 3; i++) { Console.Writeline (" Your homework grade is" + grade.hwgrade[i]) ; // ..... } } static void Main(string[] args) { int accode ; Student student = new Student() ; Course course = new Course() ; Grade grade = new Grade() ; do { Console.WriteLine(" 1. Input Student information"); Console.WriteLine(" 2. Input Course information"); Console.WriteLine(" 3. Input Grade information"); Console.WriteLine(" 4. Print Course information"); Console.WriteLine(" 5. Print Student information"); Console.WriteLine(" 6. Print Grade information"); Console.WriteLine(" 7. Print Student information including Course they are registered in and the grade obtained for that course"); Console.WriteLine(" 8. Print grade info of the course in which student has achieved the highest grade"); Console.WriteLine(" 0. Exit"); Console.WriteLine(" Please select a choice from 0-8"); accode = Console.ReadLine(); switch (accode) { case 1: student.InputStudentInfo(); break; case 2: course.InputCourseInfo(); break; case 3: grade.InputGradeInfo(); break; case 4: course.PrintCourseInfo(); break; case 5: student.PRintStudentInfo(); break; case 6: grade.PrintGradeInfo(); break; case 0: Console.WriteLine(" You have chosen to exit the program have a good day. =)"); break; } } while (accode != 0); Console.ReadKey(); } } }

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  • Do I suffer from encapsulation overuse?

    - by Florenc
    I have noticed something in my code in various projects that seems like code smell to me and something bad to do, but I can't deal with it. While trying to write "clean code" I tend to over-use private methods in order to make my code easier to read. The problem is that the code is indeed cleaner but it's also more difficult to test (yeah I know I can test private methods...) and in general it seems a bad habit to me. Here's an example of a class that reads some data from a .csv file and returns a group of customers (another object with various fields and attributes). public class GroupOfCustomersImporter { //... Call fields .... public GroupOfCustomersImporter(String filePath) { this.filePath = filePath; customers = new HashSet<Customer>(); createCSVReader(); read(); constructTTRP_Instance(); } private void createCSVReader() { //.... } private void read() { //.... Reades the file and initializes the class attributes } private void readFirstLine(String[] inputLine) { //.... Method used by the read() method } private void readSecondLine(String[] inputLine) { //.... Method used by the read() method } private void readCustomerLine(String[] inputLine) { //.... Method used by the read() method } private void constructGroupOfCustomers() { //this.groupOfCustomers = new GroupOfCustomers(**attributes of the class**); } public GroupOfCustomers getConstructedGroupOfCustomers() { return this.GroupOfCustomers; } } As you can see the class has only a constructor which calls some private methods to get the job done, I know that's not a good practice not a good practice in general but I prefer to encapsulate all the functionality in the class instead of making the methods public in which case a client should work this way: GroupOfCustomersImporter importer = new GroupOfCustomersImporter(filepath) importer.createCSVReader(); read(); GroupOfCustomer group = constructGoupOfCustomerInstance(); I prefer this because I don't want to put useless lines of code in the client's side code bothering the client class with implementation details. So, Is this actually a bad habit? If yes, how can I avoid it? Please note that the above is just a simple example. Imagine the same situation happening in something a little bit more complex.

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  • Gravity stops when side-collision detected

    - by Adrian Marszalek
    Please, look at this GIF: The label on the animation says "Move button is pressed, then released". And you can see when it's pressed (and player's getCenterY() is above wall getCenterY()), gravity doesn't work. I'm trying to fix it since yesterday, but I can't. All methods are called from game loop. public void move() { if (left) { switch (game.currentLevel()) { case 1: for (int i = 0; i < game.lvl1.getX().length; i++) game.lvl1.getX()[i] += game.physic.xVel; break; } } else if (right) { switch (game.currentLevel()) { case 1: for (int i = 0; i < game.lvl1.getX().length; i++) game.lvl1.getX()[i] -= game.physic.xVel; break; } } } int manCenterX, manCenterY, boxCenterX, boxCenterY; //gravity stop public void checkCollision() { for (int i = 0; i < game.lvl1.getX().length; i++) { manCenterX = (int) game.man.getBounds().getCenterX(); manCenterY = (int) game.man.getBounds().getCenterY(); if (game.man.getBounds().intersects(game.lvl1.getBounds(i))) { boxCenterX = (int) game.lvl1.getBounds(i).getCenterX(); boxCenterY = (int) game.lvl1.getBounds(i).getCenterY(); if (manCenterY - boxCenterY > 0 || manCenterY - boxCenterY < 0) { game.man.setyPos(-2f); game.man.isFalling = false; } } } } //left side of walls public void colliLeft() { for (int i = 0; i < game.lvl1.getX().length; i++) { if (game.man.getBounds().intersects(game.lvl1.getBounds(i))) { if (manCenterX - boxCenterX < 0) { for (int i1 = 0; i1 < game.lvl1.getX().length; i1++) { game.lvl1.getX()[i1] += game.physic.xVel; game.man.isFalling = true; } } } } } //right side of walls public void colliRight() { for (int i = 0; i < game.lvl1.getX().length; i++) { if (game.man.getBounds().intersects(game.lvl1.getBounds(i))) { if (manCenterX - boxCenterX > 0) { for (int i1 = 0; i1 < game.lvl1.getX().length; i1++) { game.lvl1.getX()[i1] += -game.physic.xVel; game.man.isFalling = true; } } } } } public void gravity() { game.man.setyPos(yVel); } //not called from gameloop: public void setyPos(float yPos) { this.yPos += yPos; }

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